Addition Within 20 Game
Add two single-digit numbers that make a total from 11 to 18, such as 8 + 5 or 9 + 9. Every question crosses ten.
Type answers on your keyboard, or tap the number pad.
Time 60Correct 0
Practise these again:
How to play
- 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.
What it practises
- Addition facts within 20
- Adding across ten
- Doubles and near doubles
Level: Grades 1–2 (ages 6–8)
Tips for adding within 20
Make ten first: 8 + 5 = 8 + 2 + 3 = 13.
Use doubles: if 6 + 6 = 12, then 6 + 7 is one more, 13.
Questions and answers
What is the “make ten” strategy?
Split the smaller number so part of it fills the bigger number up to 10. For 9 + 6, take 1 from the 6 to make 10, then add the 5 left over: 15.
What are near doubles?
Near doubles are sums where the two numbers are one apart, like 7 + 8. Double the smaller number (7 + 7 = 14) and add one more to get 15.
Why does this game skip sums below 11?
Sums within 10 have their own game. This one focuses on the harder facts that cross ten.