10 printable sets · answer key on every set

Adding Three Numbers Worksheets

CCSS 2.NBT.B.6
20 problems per set
Answer key included

What this skill is

Adding three numbers in one problem.

When it comes up: Second grade.

The mistake to watch for

Adding strictly left to right and missing easy pairs — 7 + 8 + 3 is much easier as (7 + 3) + 8.

How to help

Scan for a pair that makes ten before starting. Order does not change the total.

Next: Repeated addition, the doorway to multiplication.

A worked example

Try 7 + 5 + 3. Look for a ten: 7 + 3 = 10. Then 10 + 5 = 15. You can add in any order and the total stays the same.

Words to know

add: To put numbers together to find how many in all.
sum: The answer you get when you add.
total: All of the things added together.
order: The way things are arranged, one after another.
group: A set of things put together, like 4 groups of 3 apples.

Practice

Add all three numbers.

Showing Set 1 · 20 problems

8 + 9 + 15 =
8 + 15 + 4 =
12 + 1 + 7 =
14 + 8 + 15 =
19 + 16 + 17 =
7 + 19 + 9 =
7 + 18 + 6 =
19 + 19 + 7 =
5 + 5 + 2 =
8 + 6 + 20 =
19 + 8 + 7 =
10 + 9 + 20 =
12 + 6 + 10 =
9 + 13 + 3 =
1 + 11 + 13 =
20 + 15 + 1 =
4 + 4 + 14 =
2 + 15 + 2 =
11 + 18 + 4 =
15 + 17 + 4 =

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 2.NBT.B.6 before the sheet is built — no duplicates, and every problem falls inside the standard's number range.