[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

I’ve got a couple:

The minus turns the number around. When you have two negative signs, you turn around twice, and wind up looking forwards again. Plus two is going forwards. Minus two is turning around and then going forwards, so it takes you in the opposite direction. Minus minus two it turning around twice and then going forwards, so you go in the first direction again.

When you go from zero to two, you go two steps forwards. So 4+2 is going two steps forward from four, and 4-2 is the opposite, which is going two steps backwards from four. When you go from zero to negative two, you go to steps backwards. So 4+(-2) is two steps backwards from four, and 4-(-2) is the opposite, which is two steps forwards from four