Missing Number
Explorer I
600 · 50 to Explorer II
Work out the number that replaces ? or x, then type it.
How your rating works
- Each game has its own rating. As it climbs the questions get harder, and if it drops they get easier, so they always suit you.
- You have 60 seconds. The more you get right, and the faster you answer, the more your rating goes up.
- Playing more rounds does not raise it by itself. Only playing better does, and a weaker round can lower it.
- Everyone starts at the bottom, Explorer I. Your rating moves after every answer, so the next question already fits you. It moves fast in your first rounds of a game and settles as you play more.
- It updates the moment a round ends. As a guest it is saved on this device only, so sign in to see it on the leaderboard.
Why it helps
Finding the hidden number in a sum is early algebra in disguise and builds logical thinking.
- Number bonds
- Inverse operations
- Linear equations
Free for every student, with no sign-in needed. For Class 1-9.
Leaderboard
Best round score this week. Resets every Monday at midnight (IST).
Sign in to put your name on the board and keep your progress on every device. Games stay free either way.