Number Bonds to 20: Games, Tricks & Worksheet
Number bonds to 20 are pairs of numbers that add up to 20, like 13 + 7 and 9 + 11. Knowing them by heart makes adding, subtracting and making change much faster.
🔟 Play the number bonds to 20 game 🖨️ Printable worksheet
Tricks that make it easier
- Use bonds to 10: 3 + 7 = 10, so 13 + 7 = 20.
- Ten fingers plus ten toes make 20.
- Pairs always have the same ones digits as bonds to 10.
Try these
- 13 + ___ = 20
Answer
7 - ___ + 19 = 20
Answer
1 - 20 − 11 =
Answer
9 - ___ + 10 = 20
Answer
10 - ___ + 3 = 20
Answer
17 - 19 + ___ = 20
Answer
1
Common mistakes
- Counting instead of recalling the pair.
- Mixing up pairs that make 9 or 11 with pairs that make 10.
A five-day practice plan
| Day | What to do (10 minutes) |
|---|---|
| Day 1 | Play Number Bonds on this skill for 5–10 minutes. Read the explanation after every mistake. |
| Day 2 | Learn one trick from this page and use it out loud while you play. |
| Day 3 | Print the worksheet and try it without help. Mark it with the answer key together. |
| Day 4 | Play again and try to beat your personal best score or get three stars. |
| Day 5 | Mix it up: ask your child to explain the skill to you in their own words. |
Suits Primary 1 and Primary 2.
Frequently asked questions
What are number bonds to 20?
Pairs of whole numbers that add up to 20.
Why are number bonds important?
They are the foundation of mental maths: bridging through 10, subtraction, money and change all depend on them.
How many number bonds to 20 are there?
Counting whole numbers in both orders, there are 21 (0 + 20 up to 20 + 0).