[eli5] Trying to teach to an autistic child why 4 – (-2) is 4 +2.

Question

Title. I know it goes like that, but as an non mathematician can’t explain it to him.

In: 0

Answer 1

get 10 x red beans and 10 x green beans (or beads or something)

the red ones represent -1. the green ones represent +1. together as a pile, they all cancel each other out and equal 0.

now take away 2 x of the red beans (subtract 2 x “minus 1’s”)

now add up the pile.

for your specific question, you want to start with let’s say, 8 of the positive beans and 4 of the negative beans. added up, it equals 4. now take away 2 of the negative beans and add it up again.