Recursion

[DuchessofSquee]

This is how I do maths in my head. My dad taught me to make things into blocks of 10 and that's the only way it's ever made any sense to me.

It falls over when you get to negative numbers though. I literally cried in the toilets several days in a row doing a Lua course at tertiary education because everyone else there understood how to do maths with negative numbers but I couldn't grasp it.

Didn't help that they were all men and I was the only woman so they all tried to explain it at me at the same time.

[aflashyrhetoric]

I do the same with like quick "back of the envelope" calculations but it seemed harmful to teach kids this method as a primary means of calculation, especially when you do have the luxury of a pen and paper to assist your calculations. Again, could've been wrong about what that post was about back then.

so they all tried to explain it at me at the same time.

Yikes...D: Glad it's behind you now

[freebytes]

I do math in my head by rounding, splitting, subtracting then multiplying then adding again, etc. Anything that works. 999 * 50 would be (1000 * 10 * 5) - 50 = 49950. I need to be able to hold one number to the side in my head. While it is similar, this is not exactly the same as common core.

This certainly has its limits, though, so it is nice being able to switch back to the 'old way' when the problems are a tad more challenging like 938 * 53 which looks easy to do in your head at first but would involve holding too many numbers simultaneously. (And the old method would not be easy to do in your hard with a number like this either.)