Subtraction Within 20 Games Online Free
Take a single-digit number away from a teen number, such as 15 − 7. Every question crosses back below ten.
Type answers on your keyboard, or tap the number pad.
Practise these again:
How to play Subtraction Within 20
- Choose the 60-second challenge or untimed practice, then press Start.
- Type each answer on your keyboard or tap the number pad. It’s checked as soon as you’ve typed enough digits, or press ✓.
- Get one wrong and you’ll see the right answer, and the question comes back a little later.
- At the end, check your score and the facts to practise again.
Subtraction Within 20 skills
- Subtraction facts within 20
- Subtracting across ten
- Using addition facts to subtract
Level: Grades 1–2 (ages 6–8)
Tips for subtracting within 20
Go back to ten first: 15 − 7 = 15 − 5 − 2 = 8.
Count up to ten and on: for 13 − 9, count 9 → 10 (1) → 13 (3), so the answer is 4.
Once these are quick, mix them with addition in addition and subtraction within 20.
Subtraction Within 20 questions and answers
What does “subtracting across ten” mean?
It means the answer ends up below 10 even though you started above it, as in 14 − 6 = 8. Stopping at 10 on the way (14 − 4 − 2) makes it easier.
Which facts cause the most trouble?
Facts like 13 − 8, 15 − 7 and 17 − 9 usually cause the most trouble, because they take away more than the ones digit.
Is there a game for smaller numbers?
Yes. Subtraction Within 10 covers the basic facts, and it’s a good place to start before this game.