Subtract 2-digit numbers with regrouping

What's on the sheet

20 problems written in columns, on US Letter paper, with a box for the score. Some from sheet 1:

• 72 − 65 = 7
• 90 − 61 = 29
• 32 − 13 = 19
• 93 − 66 = 27

Helping at home

In 2nd grade, children subtract numbers like 62 − 27. There are only 2 ones, and they need to take away 7, so they trade one ten for ten ones. Now there are 5 tens and 12 ones. 12 − 7 = 5 and 5 − 2 = 3, so the answer is 35.

The most common slip is subtracting the smaller digit from the larger one in each column, so 62 − 27 becomes 45. Another is trading the ten but forgetting to cross out and lower the tens digit.

One way to help at home: before each problem, ask your child to look at the ones. "Is the top digit big enough?" If not, say the trade out loud: "I take one ten and make ten ones." Bundles of 10 straws or dimes and pennies make the trade real. Check every answer by adding it back: 35 + 27 should make 62.