kasaron:

ewig-ziege:

theorthodoxknight:

yugidoe:

blowjob-bandit:

mushj1:

何か目からウロコだなぁ

How am I just now seeing this pattern for the first time?

Because we’re not taught to think like this in schools. It’s all memorization, we’re not taught about patterns with numbers.

I feel like I’m the only one who’s known about this since forever

I was taught this trick, too.

Weird.

I never saw this pattern, I was taught that the first digit of X times 9 is one less than X, and the second digit is whatever adds to X to make 9.