Where tf was this when I was in high school?!

thats a hack for even numbers of 10. My math teacher was a sadist who used to ask us what was 19% of 31 quarts, converted into the metric system by weight.

What is this cap? It's not official

bro, my teachers had me doing math like i was trying to crack the da vinci code when it was just vibes and suffering

How Japanese students do maths

Why didn’t my teacher say that

They didn't teach you this on purpose so you would get busy taking out loans while reproducing slaves.

I have to google how to change a percentage into a decimal and I’m 70 years old

yeah, I never learned this. I learned to do it with a simple Algebra problem (X over 100 = 10 over 40, or whatever and multiplying across, then dividing by the 100. Tons of extra steps).

Nobody needs to do this because its pointless you can get the same results with by multiplying any number with decimal numbers, its much easier and more practical that way. 80 x 0.9 = 72 30 x 0.5 = 15 70 x 0.6 = 42 40 x 0.1 = 4 Try it yourself and you'll see that I'm right.

I remember trying to show this to one of my high-school teachers in 11th grade, and she got pissed at me. I used it on the board when they asked the class to solve a problem she made. Then when I used it she made me explain it and got mad instantly. I learned it from an older guy who was a machinist.