NOT LIKE THAT YOU HEATHEN

Take 7 from 7 and its 16+0 =16

This is how I think for sure.

I have no idea how normal people do it but I do

9+7

One shy of 10+7

One shy of 17

16

How do they do it?

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 think this is precisely how math is taught through Common Core now.

Because that is the joke and why the teacher reacted that way.

Or translated into reddit: woosh

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.

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 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.

More likely this is a person who was at school pre-2011 when common core was implemented.

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

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.

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.

You are probably young then. Probably schooled post 2011 when common core started being implemented.