10 printable sets · answer key on every set

3-Digit Addition Worksheets

CCSS 3.NBT.A.2
20 problems per set
Answer key included

What this skill is

Adding three-digit numbers with regrouping in one or both columns.

When it comes up: Third grade.

The mistake to watch for

Regrouping the ones correctly, then forgetting the carried digit when the tens also cross ten.

How to help

Write the carried digit above the column before adding, not after. It is easy to forget a number held only in the head.

Next: Three-digit subtraction.

A worked example

Try 346 + 278. Ones: 6 + 8 = 14, write 4 and carry 1 ten. Tens: 4 + 7 + 1 = 12, write 2 and carry 1 hundred. Hundreds: 3 + 2 + 1 = 6. The answer is 624.

Words to know

regroup: To trade 10 ones for 1 ten (or 1 ten for 10 ones) when you add or subtract.
hundred: Ten tens, written 100.
digit: One of the ten number symbols 0 to 9. The number 47 has two digits.
sum: The answer you get when you add.
estimate: To find an answer that is close, without doing the exact work.

Practice

Add. Regroup when you need to.

Showing Set 1 · 20 problems

48 + 948 =
845 + 39 =
36 + 876 =
735 + 137 =
266 + 659 =
935 + 17 =
423 + 347 =
57 + 346 =
712 + 268 =
688 + 199 =
346 + 569 =
966 + 15 =
957 + 28 =
764 + 156 =
208 + 393 =
427 + 269 =
688 + 218 =
514 + 478 =
548 + 394 =
648 + 244 =

Download this set20 problems · answer key included PDF

Answer key

All 10 sets

Each set is a different list of 20 problems with its own answer key. Use the buttons above to look at one on this page, or download any of them as a PDF.

How these sheets were made

Problems are generated for each set and checked against 3.NBT.A.2 before the sheet is built — no duplicates, and every problem falls inside the standard's number range.