Numberblocks Number Bonds - See How Numbers Split Apart

Choose a target number, tap a bond pair, and see how one whole Numberblock can split into two smaller parts.

Number bonds to:
10

Whole Numberblock 10

100%

Tap a pair to split 10 into two parts.

3 + 7 = 10

3
+
7
Rebuild in Addition

What Are Number Bonds?

Numberblocks number bonds show how one whole number can be made from two smaller parts. For example, the bonds to 10 include 1 + 9, 2 + 8, 3 + 7, 4 + 6, and 5 + 5.

After practicing bonds here, children can rebuild the same pairs in Numberblocks Addition, compare the totals on the Numberblocks 1 to 100 chart, or create the target in the Numberblocks Generator.

How to Use the Number Bonds Tool

1

Choose a Target

Pick bonds to 5, 10, 15, 20, or set your own target up to 50.

2

Pick a Bond Pair

Click any pair to split the whole Numberblock into two parts.

3

Explore All Bonds

Move through each pair and say the full equation aloud.

4

Connect to Addition

Open the addition tool to rebuild the same pair as a sum.

Number Bonds to 10 and 20

Number Bonds to 10

0 + 10 = 10
1 + 9 = 10
2 + 8 = 10
3 + 7 = 10
4 + 6 = 10
5 + 5 = 10

Number Bonds to 20

0 + 20 = 20
1 + 19 = 20
2 + 18 = 20
3 + 17 = 20
4 + 16 = 20
5 + 15 = 20
6 + 14 = 20
7 + 13 = 20
8 + 12 = 20
9 + 11 = 20
10 + 10 = 20

Why Number Bonds Matter

Mental Math Foundation

Knowing bonds to 10 helps children add and subtract without counting every block.

Parts and Wholes

Children see that a number can stay the same while its parts change.

Addition and Subtraction Link

Every bond also creates related subtraction facts, such as 10 - 7 = 3.

Frequently Asked Questions