Subtraction — Chapter Summary

Subtraction is taking away some items

Subtraction is taking away some items from a group and finding how many are left. For example, 7 − 3 means we take away 3 from 7 and count what remain

To subtract

To subtract, we can count backward from the bigger number. For example, to do 8 − 3, count back 3 steps: 7, 6, 5. So, 8 − 3 = 5.

When the top number in each

When the top number in each column is bigger, we subtract directly. For example, in 72 − 20, subtract ones: 2 − 0 = 2, then tens: 7 − 2 = 5. So, the a

When the top number is smaller

When the top number is smaller than the bottom one, we borrow 1 from the next higher place. For example, in 40 − 4, we borrow 1 ten to make 10 ones. T