Ali wrote this first step in how to add 27+12 on a hundred chart?

The first step in adding on hundred chart is find 27 and go down once because that would be ten. Then you have to go 2 numbers to the right because you already had a 10 and if you add 2 it will be 12. And we are doing addition. If you are doing a subtraction problem all you have to do is go up on how many tens you are going to subtract and go left if you have ones numbers. Hope it helps.

Main idea on left, details on right