3rd Grade Column Addition with Regrouping Worksheet: 3-Digit Sums

When a column adds up to 10 or more, only the ones digit stays. The ten moves to the next column as a small 1.

In 396 + 775, 6 + 5 = 11: write 1, carry 1. Then 9 + 7 + 1 = 17: write 7, carry 1. Last, 3 + 7 + 1 = 11. The sum is 1,171.

Sums past 1,000 go a little beyond the third grade goal, but the steps do not change.

Short numbers are the trap. In 571 + 3 and 851 + 9, the small number sits under the ones, not under the hundreds.

Let your child say each column out loud, starting from the right: ones, tens, hundreds.

If an answer looks too big or too small, round both numbers first. 549 + 969 is close to 500 + 1,000, so 1,518 makes sense.

Then check the fifteen answers with the key.

Add two prices at the shop, or the pages read this week and last week. Write the numbers in columns on a scrap of paper and let your child do the carrying.

When the page is done, praise the habit, not the speed: "You checked the ones column every time."