Trail trail · ages 7–9
Missing number puzzles for kids
Missing-number problems like 8 + ? = 15 are a child's first taste of algebra. They need to think about the relationship between numbers, not just calculate.
Number Quest's missing-number questions put the gap in different places, in both additions and subtractions.
No sign-up, no ads. Works in any browser.
What the questions practise
- Gaps in additions: 8 + ? = 15 and ? + 7 = 12
- Gaps in subtractions: 30 − ? = 3 and ? − 12 = 4
- Using the inverse operation
Try some example questions
Tap a question to see the answer and how it works.
1. Missing numbers14 − ? = 6711818
Answer: 8. 14 − 8 = 6.
2. Missing numbers? − 10 = 1824302528
Answer: 28. 28 − 10 = 18.
3. Missing numbers18 + ? = 28101578
Answer: 10. 28 − 18 = 10.
Tips for parents and teachers
- Ask: what do you add to 8 to get 15?
- Show the subtraction that solves it.
- Link it to balancing scales.
Why Number Quest
Free, with no ads and no in-app purchases. Five trails from age 5 to 16+, five ways to play, a daily goal that builds a streak, buddies to unlock and a friendly weekly leaderboard. Questions are made fresh on the device, so there is always something new.
An Android app on Google Play is coming soon. Until then, play free right here in your browser.