What this game is
Guess the Number hides a random integer in a range you choose — 1–50, 1–100 or 1–1000 — and answers every guess with "higher" or "lower". The challenge is to pin down the hidden number in as few guesses as possible, because every wrong guess is counted.
It is the classic children's game with real math inside: played well, it is a lesson in binary search, the strategy computers use to find things fast. Your best result for the 1–100 range is saved on your device.
How to play
- Choose a range and press New round to hide a number.
- Type a guess and press Guess. The game says whether the hidden number is higher or lower.
- Watch the meter: the shrinking bar shows how much of the range is still possible.
- Find the number — the fewer guesses you use, the better. Perfect play on 1–100 needs at most 7 guesses.
The optimal strategy: binary search
Halving a range of 100 numbers needs at most 7 steps (2⁷ = 128 > 100). Halving 1000 needs at most 10. If your guess count is ever above that, you are drifting from the middle — that is the game telling you to re-center.
Frequently asked questions
Is the hidden number truly random?
Yes. Each round picks a uniformly random integer in the chosen range, generated in your browser.
What is a good score?
For 1–100, consistently finishing in 5–7 guesses means you are playing binary search well. For 1–1000, 10 or fewer is excellent.
Where is my best score kept?
Locally, in your browser. Clearing site data resets it. The game also pairs well with the Percentage Calculator if you want to explore how the range shrinks — or try Number Memory and the other games.
Related calculators
Other free tools on Calculator Hub: the Arithmetic Calculator for quick sums and the Percentage Calculator for percent problems.