That's the sort of thing "new math" was trying to teach. Those sorts of breakdowns are exactly what the kids who were good at math were always doing, and teaching methods eventually caught up and realized they should just teach the tricks.
Then a bunch of parents who were bad at math asked "new math? How can math change?" The fact that they even asked that question showed how their math education was lacking, but they seem to have won.
Exactly. Math has historically relied on rote memory for most mental math. Kids would have to fill out their times tables, addition tables, etc until they memorized them. I still remember getting pop quizzes in elementary school that looked like this:
You only had two minutes to fill out the entire thing, which meant you only had 1.2 seconds per answer. You didn’t have time to actually calculate them. The point was that you were expected to have them memorized ahead of time instead of calculating each one.
But rote memory is laughably bad at actually teaching concepts. You may know that 12x5 is 60, but you don’t have any understanding on why, or other ways to do that same calculation without rote memory. And rote memory is only decently reliable up to ~12x12. Anything past that, and it becomes too much info to track; kids simply start forgetting answers.
The kids who were good at math (and I mean actually good at math, not just good at memorizing things) quickly devised methods to do this shit in our heads easily. Keeping track of multiple numbers in your head gets confusing. So “line them all up, add straight down, and carry 1’s” sort of falls apart if you’re doing it in your head. Especially if you’re trying to keep track of more than three or four numbers at a time.
Essentially, 127+248+30 is the same as 105+250+50, but the latter is much easier to parse in your head. But yeah, the parents (who primarily relied on rote memory) didn’t understand why the new method would be more effective, because they didn’t understand the concepts surrounding the math.
I think it's good to have a good set of these tables memorized and then based off those you can bounce your tricks. Eg if you know 5x12 by heart, you get 5x24 by intuition. Or even if you know 24/2 for that matter. I use simple examples but this could scale to less memorable numbers too.
I only sort of agree. I still think that by forcing you to do that, by making you practice, makes the calculations "muscle memory" in that you aren't memorizing the answers but can do the calculations faster and faster each time.
Sure. Some people could memorize them. But others will learn to calculate quickly.
Strongly disagree that memorization isn't important. It's THE foundation to be able to do effectively do more advanced stuff.
Take the equation (5678 • 9876). Use long multiplication and you only rely on doing a bunch of single digit multiplications and additions. It's so much faster to be able to instantly know each step instead of having to recalculate these "atomic" steps again and again in your head.
You generally don't need to be able to solve multiplications involving double digits in your head. It's nice-to-have but otherwise useless, as long as you're able to calculate the ballpark of the result.
For example, (38•63) is roughly 2400 and I can then calculate it on paper instead of in my head.
Head calculations are just so much more error-prone than written calculations. Don't do them if you can avoid them. There's a reason why math students (at a university) are infamous for being unable to make the simplest calculations in their head. It takes effort that could be spent somewhere else.
I would argue that memorization is important, but what you memorize and how you arrive at that is very personal. Forcing kids to memorize very specific things, and trying to enforce memorization (as opposed to the ability to arrive at the solution) seems like a bad idea to me.
I still don't have the 10x10 multiplication table memorized, and I took physics in high school and work as a programmer. I have a use for knowing number multiples, and have domain-specific numbers memorized (2^8=8*8=256, 256*256=65536), but what I don't remember off the top of my head I can figure out from the things I do know, from certain tricks, and from brute force mental math juggling numbers.
And the important thing to me is, I learned what I know not because somebody told me this is how I should do things, but because I picked them up as needed, a mix of memorizing common multiplications and figuring out tricks (like multiples of 9*N for N<11 being the digits N-1 and 10-N)
I strongly disagree that memorization is important or foundational to advanced math. It definitely is useful, but you don't need it. And the more advanced your math gets, the less valuable it becomes.
My experience is that university-level math explicitly tells you to not memorize values and formulas, but to get comfortable finding solutions directly, because then you actually learn what is going on and have methods that are universally useful.
In the real world memorization is even less useful. You will never be as fast and accurate as a calculator, or remember as many values as a precomputed table has. So why bother?
I meant basic memorization, not any advanced stuff. If you have to re-derive everything basic from scratch again and again, you will be less effective at advanced stuff.
This is not to say the basic stuff should just be memorized. Rather, it should first be understood and only then be memorized.
And definitions must be memorized, otherwise you're screwed. For instance, try proving something is a group if you forgot the definition of a group. Yes, the definitions have reason for being the way they are (which you will likely learn) but definitions just cannot be derived from your mind during an exam.
In OP's example with memorizing multiplication tables instead of doing them on-the-fly: This is a core skill required for so much later on. You don't want to waste time and energy thinking about how e.g. 7•8 = 7•2•4 = 14•4 = 14•2•2 = 28•2 = 56 because that's a quick way to lose focus. Especially if you – like me btw – have to invert a 7x7 matrix with two variables x,y put in a bunch of positions (and linear combinations of them) in an exam.
i used to hate the times table but i definitely think it's essential to mental math. even if you vaguely remember it it will help. like knowing 42 shows up somewhere in the 7x and 6x may help you remember 6x7. or if you remember a neighbor you can just add or subtract the number once. for example if you don't remember 7x6 it definitely helps to know each neighbor (both of which are easier to me since one is a 5x and one is a square number)... so either you think about 7x5 which is 35 so you can add another 7 to it or 6x6 which is 36 so you can add another 6 to it.
Oh I agree. My point wasn’t to say that rote memory is useless. I simply wanted to point out that it’s bad at teaching concepts. By teaching the concepts first, students are better prepared for later (more complicated) math courses. Anyone can memorize that 8x8 is 64, but understanding how to arrive at that answer is just as important.
I'm all for the multiple paths to solutions, but they aren't even doing times tables these days. We drill it a little at home, but he struggled with just getting it memorized. I don't know why they don't drill a little. Honestly, they seem to have the kids sitting on the computer doing adaptive math most of the time.
I was trying to explain how and why they were teaching math to a family friend and they didn't get it(multiplication stuff). I broke it down with pen and paper and they didn't get it. Simpler example, nope. Eventually I had to explain how multiplication is just repetitive addition. They responded with WHAT! and I realized why they always wore open toed shoes. I sent them a link for 5th graders.
As a parent who is bad at math, you’re not wrong. But given my kids are excelling in math (very high scores), I’ve learned to shut the fuck up about it and let the teachers do their black magic jobs.
I want to add that when I said they give away that their arguments demonstrate why math education needed to change, I do mean it. This is a clear cut case of the education system failing them.
I'd normally be happy to throw snark at the idiot things parents say that make our education system worse, but not this time.
Those sorts of breakdowns are exactly what the kids who were good at math were always doing, and teaching methods eventually caught up and realized they should just teach the tricks.
Well... kinda. "Getting to 10" was what New Math was trying to teach. So you'd take the 1 from 7 and give to 9, because 6 + 10 is easier than trying to finagle your way to 8x2.
Then a bunch of parents who were bad at math asked “new math? How can math change?”
You don't have to be bad at math, strictly speaking. But there was a lot of brute memorization in traditional math. Times Tables, for instance, were something you just memorized straight up without thinking too deeply. Getting 16 out of 7+9 was something you just had to do on your fingers until you had it lodged in your head.
Old Math tended to be slower and more tedious. New Math is more logical, but also somewhat counterintuitive until you get into the swing of it.
The fact that they even asked that question showed how their math education was lacking, but they seem to have won.
I've got friends with kids down in Houston. "New Math" appears to be alive and well, in no small part because it helps kids score higher on standardized tests.
Borrow 1 from the 7 leaving you 10 and 6. This is what they tried to teach in schools for awhile but adults weren't getting it. Common Core? Is that what they called it?
As someone who learned not via Common Core, and then found out Common Core taught math how I taught myself to do mental math I was a little envious that kids would learn my “easier” method.
Yup, helping my kiddo with the math portion of Common Core was like seeing professionals finally understanding how easy it is to sort numbers to make stuff easier instead of doing a bunch of rote memorization of tables. Also teaching kids to estimate to know if your math is way off!
Common Core for math was awesome. That was the only one I had to help with so no idea about the rest.
Well it's good for some shorthand but anything complicated you need either a calculator or do it long hand. With calculators everywhere they may have just switched to "hey fun mental ways to think about it because no one does long hand anyway".
No, the same fundamental concepts works extremely well for multiplication of large numbers and long division, both of which don't have a memorization option. It also helps with catching typos when using a calculator.
Easy long numbers yes, complicated long numbers I'm gonna say no. I'm not even saying large numbers, I'm saying long numbers which can include decimal points. And the chance of mistakes goes way up. There's no point of doing it mentally or by hand when calculators are ubiquitous. I think this is why they switched to different ways of thinking about math, rather than hard core hand calculations that no one is going to do anyway.
Decimal points don't make it more complicated when you understand the fundamentals.
Using a calculator is not a different way of thinking. You have to understand the math to know whether the calculator is being used correctly, the calculator just makes it faster.
One of my wifes friends was an elemetry school teacher when common core was popular. We asked her what it was and as she was explaining it, i said, "oh, like how you do mental math?"
Im an engineer and i just assumed thats how everyone did math... apparently people just memorized everything
Yeah, when I went through school they didn’t teach it this why but that is what I taught myself, much more simple math (+ & - with no * or \) in the same amount of steps.
Is that what they call Common Core? I’ve heard the term but didn’t know how it changed the method of teaching math.
Leave it to my AuDHD brain to figure out a less strenuous path to the same endpoint…
I wonder if this is an anxiety source for ASD/ADHD/AuDHD people. Having to constantly re-map lessons taught to fit my neurodivergent brain that it now feels like the entire neurotypical world is gaslighting neurodivergents.
Is that what they call Common Core? I’ve heard the term but didn’t know how it changed the method of teaching math.
Common core showed multiple ways that were intended to increase the understanding of how math works. This was one of the ways that was presented which wasn't how they taught it when I was a kid. There were at least two that I remember when my kiddo was doing common core:
Double one of the numbers and add or subtract the difference between them (7 is two less than 9, so 9x9 then subtract 2)
Take enough from the smaller number to reach 10 and add what is left (9+7 to 10+6)
A very similar concept for tipping about 20% is taking 1/10th of the bill by moving the decimal one to the left and doubling that. To make it even easier for me I just round to the nearest $10 amount first.
Bill: $66.20 -> move left and round up = $7.00 and double to $14.00. The exact 20% amount is a little over $13 but I tend to round up because it is also faster to add whole dollars to the bill.
Maybe you got lucky then, because when I was a kid, rote memorization was the only way teachers would accept the answer. If you changed the problem to 10 + 6 or the one op posted, the teacher would tell you that you did it wrong. This is why I just decided to do this regrouping in my head and just write what the teacher wanted because I would get the right answer anyway and not get told it was wrong.
Oh yes very lucky!! I had some really amazing teachers. they really made me enjoy maths and science and all that hard shit, and rewarded that kinda thinking. Cause what you just mentioned is so demoralizing
Even had a maths teacher who was kinda a prick (for other reasons) but he was the one that encouraged that kinda thinking the most
This way of thinking is just a different way of doing math and has absolutely nothing to do with ADHD. This type of post is likely responsible for a large portion of the people self diagnosing themselves with something that I struggle with.
OPs description is literally the simplest example of the dreaded "new math" they are teaching in schools.
9+7 is the same as 9+1+6 is the same as 10+6 is 16. New math. Same as the old math.
ETA: one of the points of "new math", iirc, is essentially to teach all kids to use the methods that the kids who are "naturally gifted" at arithmetic sort of figured out on their own. So, congrats?
It's less about "changing the way we do math" and more about "teaching kids to break down problems to their simplest elements"...which is an all-around important life skill, aside from just math.
For the last fifteen years, the emphasis in math teaching is that all methods to the right answer are correct. Emphasis is on sharing all the different methods. (Canada)
That is what Common Core in the US was attempting to do, show several approaches including the one in the OP to help understand how match works instead of teaching the 'one true way' that was common prior.
That's exactly what it is. A way to help conceptualize and play with numbers. Stuff my bored ass was doing in school anyway before common core came around lol
I mean, sure, the choice of the "nice" numbers here is eccentric, but this is essentially the way math is taught nowadays. Only, instead of making 8 in this special case, the goal is usually to make 10 + leftovers because adding to 10 is always easy.
Here's my (upper midwest) spicy mental math take: it should be big-endian and solved with backtracking for ripple carry/borrow. None of this starting-from-the-1's-place-and-successively-incorporating-higher-order-digits nonsense. Extended carry/borrow is rare, and if you start with the most significant digits and give up/get bored part way through, the intermediate answer is in the ballpark of the real answer.
Your teachers are bad at their job. There is nothing wrong with that method. Now, if you also try to do 7+3 as 5+5, you might need to learn other method so next time, you choose a more efficient one. But against that would not be wrong.
Especially since the thrust of the new math curriculum seems to be more about being nimble with numbers and being able to conceptualize and compartmentalize their values rather than learning rote formula.
I assume they just don't. For my mom at least, she absolutely will not apply mental effort to anything that doesn't strictly require it. If a mental task can be offloaded to someone or something else, she'll do that instead, every time.
I used to work at a gas station, and I was always giving different amounts of change, and so I accidentally memorized every single possible combination of digits and coins from 1 to 99.
122 Comments
frezik@lemmy.blahaj.zone · 144 pts · 312d
That's the sort of thing "new math" was trying to teach. Those sorts of breakdowns are exactly what the kids who were good at math were always doing, and teaching methods eventually caught up and realized they should just teach the tricks.
Then a bunch of parents who were bad at math asked "new math? How can math change?" The fact that they even asked that question showed how their math education was lacking, but they seem to have won.
mic_check_one_two@lemmy.dbzer0.com · 59 pts · 312d
Exactly. Math has historically relied on rote memory for most mental math. Kids would have to fill out their times tables, addition tables, etc until they memorized them. I still remember getting pop quizzes in elementary school that looked like this:
You only had two minutes to fill out the entire thing, which meant you only had 1.2 seconds per answer. You didn’t have time to actually calculate them. The point was that you were expected to have them memorized ahead of time instead of calculating each one.
But rote memory is laughably bad at actually teaching concepts. You may know that 12x5 is 60, but you don’t have any understanding on why, or other ways to do that same calculation without rote memory. And rote memory is only decently reliable up to ~12x12. Anything past that, and it becomes too much info to track; kids simply start forgetting answers.
The kids who were good at math (and I mean actually good at math, not just good at memorizing things) quickly devised methods to do this shit in our heads easily. Keeping track of multiple numbers in your head gets confusing. So “line them all up, add straight down, and carry 1’s” sort of falls apart if you’re doing it in your head. Especially if you’re trying to keep track of more than three or four numbers at a time.
Essentially, 127+248+30 is the same as 105+250+50, but the latter is much easier to parse in your head. But yeah, the parents (who primarily relied on rote memory) didn’t understand why the new method would be more effective, because they didn’t understand the concepts surrounding the math.
boonhet@sopuli.xyz · 12 pts · 312d
I think it's good to have a good set of these tables memorized and then based off those you can bounce your tricks. Eg if you know 5x12 by heart, you get 5x24 by intuition. Or even if you know 24/2 for that matter. I use simple examples but this could scale to less memorable numbers too.
pyre@lemmy.world · 2 pts · 311d
x5 has its own trick, for me it's ÷2x10 (or x10÷2, whichever feels more intuitive) so 5x24 => 24/2 => 12x10 = 120
brygphilomena@lemmy.dbzer0.com · 5 pts · 312d
I only sort of agree. I still think that by forcing you to do that, by making you practice, makes the calculations "muscle memory" in that you aren't memorizing the answers but can do the calculations faster and faster each time.
Sure. Some people could memorize them. But others will learn to calculate quickly.
yetAnotherUser@discuss.tchncs.de · 5 pts · 312d
Strongly disagree that memorization isn't important. It's THE foundation to be able to do effectively do more advanced stuff.
Take the equation (5678 • 9876). Use long multiplication and you only rely on doing a bunch of single digit multiplications and additions. It's so much faster to be able to instantly know each step instead of having to recalculate these "atomic" steps again and again in your head.
You generally don't need to be able to solve multiplications involving double digits in your head. It's nice-to-have but otherwise useless, as long as you're able to calculate the ballpark of the result.
For example, (38•63) is roughly 2400 and I can then calculate it on paper instead of in my head.
Head calculations are just so much more error-prone than written calculations. Don't do them if you can avoid them. There's a reason why math students (at a university) are infamous for being unable to make the simplest calculations in their head. It takes effort that could be spent somewhere else.
kuberoot@discuss.tchncs.de · 3 pts · 310d
I would argue that memorization is important, but what you memorize and how you arrive at that is very personal. Forcing kids to memorize very specific things, and trying to enforce memorization (as opposed to the ability to arrive at the solution) seems like a bad idea to me.
I still don't have the 10x10 multiplication table memorized, and I took physics in high school and work as a programmer. I have a use for knowing number multiples, and have domain-specific numbers memorized (2^8=8*8=256, 256*256=65536), but what I don't remember off the top of my head I can figure out from the things I do know, from certain tricks, and from brute force mental math juggling numbers.
And the important thing to me is, I learned what I know not because somebody told me this is how I should do things, but because I picked them up as needed, a mix of memorizing common multiplications and figuring out tricks (like multiples of 9*N for N<11 being the digits N-1 and 10-N)
kattfisk@lemmy.dbzer0.com · 2 pts · 311d
I strongly disagree that memorization is important or foundational to advanced math. It definitely is useful, but you don't need it. And the more advanced your math gets, the less valuable it becomes.
My experience is that university-level math explicitly tells you to not memorize values and formulas, but to get comfortable finding solutions directly, because then you actually learn what is going on and have methods that are universally useful.
In the real world memorization is even less useful. You will never be as fast and accurate as a calculator, or remember as many values as a precomputed table has. So why bother?
yetAnotherUser@discuss.tchncs.de · 3 pts · 311d
I meant basic memorization, not any advanced stuff. If you have to re-derive everything basic from scratch again and again, you will be less effective at advanced stuff.
This is not to say the basic stuff should just be memorized. Rather, it should first be understood and only then be memorized.
And definitions must be memorized, otherwise you're screwed. For instance, try proving something is a group if you forgot the definition of a group. Yes, the definitions have reason for being the way they are (which you will likely learn) but definitions just cannot be derived from your mind during an exam.
In OP's example with memorizing multiplication tables instead of doing them on-the-fly: This is a core skill required for so much later on. You don't want to waste time and energy thinking about how e.g. 7•8 = 7•2•4 = 14•4 = 14•2•2 = 28•2 = 56 because that's a quick way to lose focus. Especially if you – like me btw – have to invert a 7x7 matrix with two variables x,y put in a bunch of positions (and linear combinations of them) in an exam.
Edit: substitute unescaped *s with •
pyre@lemmy.world · 5 pts · 311d
i used to hate the times table but i definitely think it's essential to mental math. even if you vaguely remember it it will help. like knowing 42 shows up somewhere in the 7x and 6x may help you remember 6x7. or if you remember a neighbor you can just add or subtract the number once. for example if you don't remember 7x6 it definitely helps to know each neighbor (both of which are easier to me since one is a 5x and one is a square number)... so either you think about 7x5 which is 35 so you can add another 7 to it or 6x6 which is 36 so you can add another 6 to it.
mic_check_one_two@lemmy.dbzer0.com · 3 pts · 311d
Oh I agree. My point wasn’t to say that rote memory is useless. I simply wanted to point out that it’s bad at teaching concepts. By teaching the concepts first, students are better prepared for later (more complicated) math courses. Anyone can memorize that 8x8 is 64, but understanding how to arrive at that answer is just as important.
pyre@lemmy.world · 1 pts · 311d
yeah obviously, but i thought they were supposed to teach the times table after multiplication in general anyway
TempermentalAnomaly@lemmy.world · 1 pts · 311d
I'm all for the multiple paths to solutions, but they aren't even doing times tables these days. We drill it a little at home, but he struggled with just getting it memorized. I don't know why they don't drill a little. Honestly, they seem to have the kids sitting on the computer doing adaptive math most of the time.
baldingpudenda@lemmy.world · 31 pts · 312d
I was trying to explain how and why they were teaching math to a family friend and they didn't get it(multiplication stuff). I broke it down with pen and paper and they didn't get it. Simpler example, nope. Eventually I had to explain how multiplication is just repetitive addition. They responded with WHAT! and I realized why they always wore open toed shoes. I sent them a link for 5th graders.
dohpaz42@lemmy.world · 12 pts · 312d
Hey! Nothing wrong with open toed shoes damnit.
Mouselemming@sh.itjust.works · 6 pts · 312d
I'm not very good at math (but not an idiot like your example) and I wear flip-flops every day of the year but they're not related.
Are you trying to say something like "too dumb to tie shoelaces?"
Because there are quite a lot of lace-up open toe shoes and sandals, as well as closed toe shoes without laces, so that doesn't track.
brygphilomena@lemmy.dbzer0.com · 12 pts · 312d
Can you count to 20 with your shoes on?
Mouselemming@sh.itjust.works · 6 pts · 312d
I can count to 20 with my eyes shut but my toes can't breathe with shoes on.
dohpaz42@lemmy.world · 19 pts · 312d
As a parent who is bad at math, you’re not wrong. But given my kids are excelling in math (very high scores), I’ve learned to shut the fuck up about it and let the teachers do their
black magicjobs.frezik@lemmy.blahaj.zone · 4 pts · 312d
I want to add that when I said they give away that their arguments demonstrate why math education needed to change, I do mean it. This is a clear cut case of the education system failing them.
I'd normally be happy to throw snark at the idiot things parents say that make our education system worse, but not this time.
UnderpantsWeevil@lemmy.world · 7 pts · 312d
Well... kinda. "Getting to 10" was what New Math was trying to teach. So you'd take the 1 from 7 and give to 9, because 6 + 10 is easier than trying to finagle your way to 8x2.
You don't have to be bad at math, strictly speaking. But there was a lot of brute memorization in traditional math. Times Tables, for instance, were something you just memorized straight up without thinking too deeply. Getting 16 out of 7+9 was something you just had to do on your fingers until you had it lodged in your head.
Old Math tended to be slower and more tedious. New Math is more logical, but also somewhat counterintuitive until you get into the swing of it.
I've got friends with kids down in Houston. "New Math" appears to be alive and well, in no small part because it helps kids score higher on standardized tests.
TheRealKuni@piefed.social · 1 pts · 312d
limonade@jlai.lu · 1 pts · 312d
Never heard about new math. Where does this method comes from (geographically)?
Mouselemming@sh.itjust.works · 5 pts · 312d
The deep past https://en.m.wikipedia.org/wiki/New_Math
tigeruppercut@lemmy.zip · 3 pts · 312d
deep indeed
https://www.youtube.com/watch?v=UIKGV2cTgqA
Mouselemming@sh.itjust.works · 3 pts · 310d
Always upvote Tom Lehrer!
limonade@jlai.lu · 2 pts · 310d
Thank you.
NewPerspective@lemmy.world · 69 pts · 312d
Borrow 1 from the 7 leaving you 10 and 6. This is what they tried to teach in schools for awhile but adults weren't getting it. Common Core? Is that what they called it?
TheMinions@lemmy.dbzer0.com · 48 pts · 312d
As someone who learned not via Common Core, and then found out Common Core taught math how I taught myself to do mental math I was a little envious that kids would learn my “easier” method.
someguy3@lemmy.world · 23 pts · 312d
Same, common core is what I came up with to do mental math.
snooggums@piefed.world · 14 pts · 312d
Yup, helping my kiddo with the math portion of Common Core was like seeing professionals finally understanding how easy it is to sort numbers to make stuff easier instead of doing a bunch of rote memorization of tables. Also teaching kids to estimate to know if your math is way off!
Common Core for math was awesome. That was the only one I had to help with so no idea about the rest.
someguy3@lemmy.world · -1 pts · 312d
Well it's good for some shorthand but anything complicated you need either a calculator or do it long hand. With calculators everywhere they may have just switched to "hey fun mental ways to think about it because no one does long hand anyway".
snooggums@piefed.world · 4 pts · 312d
No, the same fundamental concepts works extremely well for multiplication of large numbers and long division, both of which don't have a memorization option. It also helps with catching typos when using a calculator.
someguy3@lemmy.world · 1 pts · 312d
Easy long numbers yes, complicated long numbers I'm gonna say no. I'm not even saying large numbers, I'm saying long numbers which can include decimal points. And the chance of mistakes goes way up. There's no point of doing it mentally or by hand when calculators are ubiquitous. I think this is why they switched to different ways of thinking about math, rather than hard core hand calculations that no one is going to do anyway.
snooggums@piefed.world · 3 pts · 312d
Decimal points don't make it more complicated when you understand the fundamentals.
Using a calculator is not a different way of thinking. You have to understand the math to know whether the calculator is being used correctly, the calculator just makes it faster.
Sc00ter@lemmy.zip · 5 pts · 311d
One of my wifes friends was an elemetry school teacher when common core was popular. We asked her what it was and as she was explaining it, i said, "oh, like how you do mental math?"
Im an engineer and i just assumed thats how everyone did math... apparently people just memorized everything
nixon@sh.itjust.works · 4 pts · 312d
Yeah, when I went through school they didn’t teach it this why but that is what I taught myself, much more simple math (+ & - with no * or \) in the same amount of steps.
Is that what they call Common Core? I’ve heard the term but didn’t know how it changed the method of teaching math.
Leave it to my AuDHD brain to figure out a less strenuous path to the same endpoint…
I wonder if this is an anxiety source for ASD/ADHD/AuDHD people. Having to constantly re-map lessons taught to fit my neurodivergent brain that it now feels like the entire neurotypical world is gaslighting neurodivergents.
ech@lemmy.ca · 4 pts · 312d
Just a heads up, your \ got absorbed by the text markdown Lemmy uses. You have to use a double slash to have it show up, like this
\\.nixon@sh.itjust.works · 4 pts · 312d
Fixed, thanks again!
nixon@sh.itjust.works · 4 pts · 312d
Oh, thanks so much for the heads up. I didn’t know that!
ech@lemmy.ca · 4 pts · 312d
Sure thing! It's not a particularly well-known thing, tbh, so it slips into comments now and again.
snooggums@piefed.world · 3 pts · 312d
Common core showed multiple ways that were intended to increase the understanding of how math works. This was one of the ways that was presented which wasn't how they taught it when I was a kid. There were at least two that I remember when my kiddo was doing common core:
Ashenlux@lemmy.blahaj.zone · 51 pts · 312d
Why wouldn't you just take 1 from 7, add it to 9, and make it 10 + 6? That makes a lot more sense to my brain at least.
minkymunkey_7_7@lemmy.world · 21 pts · 312d
He's a spider monkey with base 8 fingers.
prex@aussie.zone · 11 pts · 312d
https://xkcd.com/1530/
Natanox@discuss.tchncs.de · 11 pts · 312d
Because making shit equal, be in perfect balance or even symmetric makes my dopamine go 🥳.
Finding the correct answer that way is a neat side effect too.
xorollo@leminal.space · 1 pts · 311d
Multiplying by two is a similar cognitive exercise to adding 10 in small numbers (for me) so it would really depend on which occured to me first.
groet@feddit.org · 2 pts · 311d
Because that is the joke and why the teacher reacted that way.
Or translated into reddit: woosh
Akasazh@lemmy.world · 43 pts · 312d
This is all incorrect because 7 would inevitably cannibalize 9.
hakunawazo@lemmy.world · 24 pts · 312d
boonhet@sopuli.xyz · 4 pts · 312d
That's why you instead take 1 from 7 and give to 9, making it 10+6
You can't allow the 8 into the same house as 7 and 9.
justOnePersistentKbinPlease@fedia.io · 35 pts · 312d
9+anything
10+x-1
Similarly for 8+x is 10+x-2
Multiplying by 5: mult by 10 divide by 2 Mult by 15: mult by 10, add half of that.
snooggums@piefed.world · 6 pts · 312d
A very similar concept for tipping about 20% is taking 1/10th of the bill by moving the decimal one to the left and doubling that. To make it even easier for me I just round to the nearest $10 amount first.
Bill: $66.20 -> move left and round up = $7.00 and double to $14.00. The exact 20% amount is a little over $13 but I tend to round up because it is also faster to add whole dollars to the bill.
yakko@feddit.uk · 4 pts · 312d
I only read this thread to make sure someone was right. Thank you
wfh@piefed.zip · 23 pts · 312d
Heretic here. I just do 10 + 7 - 1.
schema@lemmy.world · 5 pts · 312d
That's how I do it in my head too. Is this even uncommon?
PotatoesFall@discuss.tchncs.de · 5 pts · 312d
No many people have their own methods. I don't think this is exclusive to ADHD whatsoever
limonade@jlai.lu · 1 pts · 312d
That's okay.
Mangoholic@lemmy.ml · 21 pts · 311d
No take one from 7 and its 10+6=16
nexguy@lemmy.world · 26 pts · 311d
Take 7 from 7 and its 16+0 =16
InnerScientist@lemmy.world · 5 pts · 311d
Valmond@lemmy.world · 4 pts · 311d
Take 11 from 7 and it is 20-4=16
billwashere@lemmy.world · 2 pts · 311d
This is how I think for sure.
Bubbaonthebeach@lemmy.ca · 19 pts · 311d
Why wouldn't you take the 1 from the 7 so it is 10+6?
Lucky_777@lemmy.world · 7 pts · 311d
This is what I go for...Just play in 10s. Alot easier IMO
thermal_shock@lemmy.world · 4 pts · 311d
NOT LIKE THAT YOU HEATHEN
ayyy@sh.itjust.works · 16 pts · 312d
You’re so adhd you forgot that this was a whole part of your math curriculum that you just tuned out because you already knew it.
Pandantic@midwest.social · 3 pts · 311d
More likely this is a person who was at school pre-2011 when common core was implemented.
pyre@lemmy.world · 16 pts · 311d
not even ADHD related you're just taking a route to something more readily available in your memory. that's how brains are supposed to work.
to me the detour is -1+10. whenever i see a 9 i take 1 away from the other guy and then add 10.
9 x single digit mumber works similarly; except i take away 1 and complete that to 9 by adding a number next to it.
9x7 = ?
7-1 = 6
6+? = 9
9x7 = 63
Labna@lemmy.world · 1 pts · 311d
9x7 = 70 - 7 = 63 in table of 9 too easy ! (nearly the same technic)
8x7 = 70 - 7x2 = 70 - 14 = 6 + 70 - 20 = 56 (6 from 10-4 from 14)
7x6 = 5x7 + 7 = 70/2 +7 = 35 + 7 = 42 the answer to the life, the death and all the rest (5xa = 10/2 x a= 10a/2)
pyre@lemmy.world · 1 pts · 311d
i mentioned the 5x trick elsewhere under this post but for me for some reason doing the halfing first is easier. so to me it's a/2x10 instead.
slacktoid@lemmy.ml · 15 pts · 312d
My maths teachers encouraged that kinda calculations tbh... Makes sense why I like maths
Pandantic@midwest.social · 1 pts · 311d
You are probably young then. Probably schooled post 2011 when common core started being implemented.
slacktoid@lemmy.ml · 2 pts · 311d
Hmm no I'm not
Pandantic@midwest.social · 1 pts · 311d
Maybe you got lucky then, because when I was a kid, rote memorization was the only way teachers would accept the answer. If you changed the problem to 10 + 6 or the one op posted, the teacher would tell you that you did it wrong. This is why I just decided to do this regrouping in my head and just write what the teacher wanted because I would get the right answer anyway and not get told it was wrong.
slacktoid@lemmy.ml · 2 pts · 308d
Oh yes very lucky!! I had some really amazing teachers. they really made me enjoy maths and science and all that hard shit, and rewarded that kinda thinking. Cause what you just mentioned is so demoralizing
Even had a maths teacher who was kinda a prick (for other reasons) but he was the one that encouraged that kinda thinking the most
ObtuseDoorFrame@lemmy.zip · 14 pts · 312d
This way of thinking is just a different way of doing math and has absolutely nothing to do with ADHD. This type of post is likely responsible for a large portion of the people self diagnosing themselves with something that I struggle with.
Stop posting this shit.
474D@lemmy.world · 2 pts · 312d
Same for like 60% of stuff on this community tbh
DragonTypeWyvern@midwest.social · 4 pts · 312d
I don't believe you have the numbers to back that claim up, misinformation spreader!
zaknenou@lemmy.dbzer0.com · 14 pts · 311d
I thought you give 1 from 7 to 9 so it becomes 10+6 !!
lka1988@lemmy.dbzer0.com · 1 pts · 310d
You can do that, too.
fodor@lemmy.zip · 11 pts · 312d
JasonDJ@lemmy.zip · 19 pts · 312d
OPs description is literally the simplest example of the dreaded "new math" they are teaching in schools.
9+7 is the same as 9+1+6 is the same as 10+6 is 16. New math. Same as the old math.
ETA: one of the points of "new math", iirc, is essentially to teach all kids to use the methods that the kids who are "naturally gifted" at arithmetic sort of figured out on their own. So, congrats?
It's less about "changing the way we do math" and more about "teaching kids to break down problems to their simplest elements"...which is an all-around important life skill, aside from just math.
RebekahWSD@lemmy.world · 5 pts · 312d
A very good song by Tom Lehrer as well.
Quilotoa@lemmy.ca · 10 pts · 312d
For the last fifteen years, the emphasis in math teaching is that all methods to the right answer are correct. Emphasis is on sharing all the different methods. (Canada)
snooggums@piefed.world · 2 pts · 312d
That is what Common Core in the US was attempting to do, show several approaches including the one in the OP to help understand how match works instead of teaching the 'one true way' that was common prior.
Omega_Jimes@lemmy.ca · 9 pts · 312d
This is actually how my professor, who has a PhD in mathematics, does math.
nucleative@lemmy.world · 6 pts · 310d
A dozen years ago or so there was a huge uproar about "common core" mathematics, which was a new standard being used in the USA for teaching.
It was a politicized trendy topic and even so-called-intellectuals were jumping on the train and calling it a deranged way of learning math.
I looked into it a bit, and I swear this pic pretty much sums up one of the key methods they were teaching.
Basically just tricks that a lot of people figure out to simplify problems.
tlmcleod@lemmy.ml · 3 pts · 310d
That's exactly what it is. A way to help conceptualize and play with numbers. Stuff my bored ass was doing in school anyway before common core came around lol
lka1988@lemmy.dbzer0.com · 2 pts · 310d
Common core is still a thing. I wish I had common core as a kid. Makes way more sense.
Archangel1313@lemmy.ca · 6 pts · 311d
This is literally how common core math works.
AniZaeger@lemmy.world · 6 pts · 311d
And here I always thought it was 1001 + 0111 = 10000.
TempermentalAnomaly@lemmy.world · 6 pts · 311d
The answer is 69
420% of the time.
PattyMcB@lemmy.world · 1 pts · 310d
Niiiiice
Adderbox76@lemmy.ca · 6 pts · 312d
9+9-2
Stamets@lemmy.dbzer0.com · 7 pts · 312d
Just as acceptable
BigDanishGuy@sh.itjust.works · 5 pts · 312d
My retarded ass: 9 is 0b1001 and 7 is 0b111, 0b1001+0b111 is 0b10000 which is 16.
Am kidding, I take 9's ten friend, sub-stract that from 7 et voilà I have 6 ones and 1 ten which is 16.
ornery_chemist@mander.xyz · 5 pts · 311d
I mean, sure, the choice of the "nice" numbers here is eccentric, but this is essentially the way math is taught nowadays. Only, instead of making 8 in this special case, the goal is usually to make 10 + leftovers because adding to 10 is always easy.
Here's my (upper midwest) spicy mental math take: it should be big-endian and solved with backtracking for ripple carry/borrow. None of this starting-from-the-1's-place-and-successively-incorporating-higher-order-digits nonsense. Extended carry/borrow is rare, and if you start with the most significant digits and give up/get bored part way through, the intermediate answer is in the ballpark of the real answer.
Soulg@ani.social · 5 pts · 311d
I've always done it this way and don't have adhd
PattyMcB@lemmy.world · 4 pts · 310d
9 is one less than 10, and 7 is three less than 10, so combined, they're four less than 20 = 16
Raiderkev@lemmy.world · 4 pts · 311d
This is psychopathy. Clearly you just add the 1 to the 9 to make it 10 and subtract it from the 7 to get 6 and 10+6 = 16.
limonade@jlai.lu · 4 pts · 312d
Your teachers are bad at their job. There is nothing wrong with that method. Now, if you also try to do 7+3 as 5+5, you might need to learn other method so next time, you choose a more efficient one. But against that would not be wrong.
bizarroland@lemmy.world · 3 pts · 312d
Especially since the thrust of the new math curriculum seems to be more about being nimble with numbers and being able to conceptualize and compartmentalize their values rather than learning rote formula.
brucethemoose@lemmy.world · 4 pts · 311d
Holy shit.
Is that not how “normal” people do math in their head? How do they do it?
blockheadjt@sh.itjust.works · 5 pts · 311d
I have no idea how normal people do it but I do
9+7
One shy of 10+7
One shy of 17
16
Whats_your_reasoning@lemmy.world · 4 pts · 311d
I assume they just don't. For my mom at least, she absolutely will not apply mental effort to anything that doesn't strictly require it. If a mental task can be offloaded to someone or something else, she'll do that instead, every time.
BreadOven@lemmy.world · 4 pts · 310d
10 + 7 = 17 17- 1 = 16
proton_lynx@lemmy.world · 2 pts · 293d
This is the way
molten@lemmy.world · 3 pts · 312d
Is this engagement bait to get all the people who do it differently because it worked lol
menas@lemmy.wtf · 3 pts · 310d
The legend said that it is how Gaussian elimination was discovered in europe
Reverendender@sh.itjust.works · 3 pts · 312d
That’s the most logical way! They are the heathens!
ericheese@lemmy.ml · 3 pts · 312d
I do it like 7-1=6 and 9+1=10 and 10+6=16
bizarroland@lemmy.world · 3 pts · 312d
I used to work at a gas station, and I was always giving different amounts of change, and so I accidentally memorized every single possible combination of digits and coins from 1 to 99.
I no longer have to think, I have a lookup table.
slacktoid@lemmy.ml · 2 pts · 312d
You made a change rainbow table!!! Love it!
dotslashme@infosec.pub · 2 pts · 312d
As long as your method gives you the correct answer, I see no need to correct anyone.
gravitas_deficiency@sh.itjust.works · 2 pts · 312d
lol yep, precisely
laserm@lemmy.world · 2 pts · 311d
Me: so 9 is 10-1 so you can do 10+7=17 and take away one so 16
FryHyde@lemmy.zip · 2 pts · 311d
I think this is precisely how math is taught through Common Core now.
futurefossil@lemmy.world · 2 pts · 310d
Idk I have adhd and my working memory is so poor that memorizing time tables was the only way. :/
Psaldorn@lemmy.world · 1 pts · 312d
For whatever reasons numbers fall out of my short term memory and odd numbers even moreso.
phoenixz@lemmy.ca · 1 pts · 312d
AI does this like someone having ADHD while on meth.
Windex007@lemmy.world · 4 pts · 312d
Just wait until you find out what people with ADHD are prescribed