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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.
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.
More likely this is a person who was at school pre-2011 when common core was implemented.
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.
He’s a spider monkey with base 8 fingers.
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.
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.
Said by someone who never actually told that to a teacher, lol.
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.
A very good song by Tom Lehrer as well.
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.
It’s really helpful for quadratic factoring, too, since knowing at a glance that –56 is ±7 × ±8 keeps your working memory free to actually focus on the mathematical skills/concepts/problem.
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 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 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.
It frees you up to do more complicated arithmetic. Geometry would be too slow if you didn’t innately understand
3*60=180. Which you don’t get without3*6=18
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.
Hey! Nothing wrong with open toed shoes damnit.
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.
Can you count to 20 with your shoes on?
I can count to 20 with my eyes shut but my toes can’t breathe with shoes on.
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.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.
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Never heard about new math. Where does this method comes from (geographically)?
The deep past https://en.m.wikipedia.org/wiki/New_Math
deep indeed
This is all incorrect because 7 would inevitably cannibalize 9.
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.
My maths teachers encouraged that kinda calculations tbh… Makes sense why I like maths
You are probably young then. Probably schooled post 2011 when common core started being implemented.
It’s basically “common core” math (in the US), or just “updated curriculum” everywhere else in the world. Turns out that building fluency with math through play and number decomposition is incredibly powerful for long-term learning.
This is actually how my professor, who has a PhD in mathematics, does math.
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.
Same, common core is what I came up with to do mental math.
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.
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)
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
\\.Fixed, thanks again!
Oh, thanks so much for the heads up. I didn’t know that!
Sure thing! It’s not a particularly well-known thing, tbh, so it slips into comments now and again.
9+anything
10+x-1Similarly 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.
Multiplying by 5: mult by 10 divide by 2
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.
I only read this thread to make sure someone was right. Thank you
I do it like 7-1=6 and 9+1=10 and 10+6=16
This is encouraged in ‘new math’! Kids are explicitly taught and validated in using these compensation strategies instead of feeling like they are doing something wrong.
Well that would have helped me back in the 2000’s when i was told i worked out maths problems differently to everyone else with this sort of method even though i got the same answers. One teacher had me show my working out for a bunch of problems to understand how i was doing it and it made me internally feel bad at maths because i did it ‘wrong’.
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.
Same for like 60% of stuff on this community tbh
I don’t believe you have the numbers to back that claim up, misinformation spreader!
Heretic here. I just do 10 + 7 - 1.
That’s how I do it in my head too. Is this even uncommon?
No many people have their own methods. I don’t think this is exclusive to ADHD whatsoever
That’s okay.
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.
Actually, no. One of the core goals of the US Common Core math standards is to make explicit this type of compensation strategy. One of the main ones emphasized for addition/subtraction is ‘taking from/completing a ten’ but there is a lot of work to help kids internalize these kinds of doubles strategies!
Ever think that maybe this person was schooled befor 2011 when common core math was implemented?
