Guess the number 1 to 1,000
A secret number between 1 and 1,000. Perfect play needs 10 guesses. How close can you get?
Your name, guesses and time go on today's public board.
How it works
Guess a number between 1 and 1,000
Same rules as the classic game, ten times the numbers. After each guess you see bigger or smaller, and the bar shows what is left. Because each good guess halves the range, going from 100 to 1,000 numbers adds only 3 guesses.
Strategy
The 10 guess plan
This is a worst case game with the secret number 637. Even here, guessing the middle finds it on guess 10:
| Guess | Answer | Still possible |
|---|---|---|
| 500 | ↑ Bigger | 501 to 1,000 |
| 750 | ↓ Smaller | 501 to 749 |
| 625 | ↑ Bigger | 626 to 749 |
| 687 | ↓ Smaller | 626 to 686 |
| 656 | ↓ Smaller | 626 to 655 |
| 640 | ↓ Smaller | 626 to 639 |
| 632 | ↑ Bigger | 633 to 639 |
| 636 | ↑ Bigger | 637 to 639 |
| 638 | ↓ Smaller | 637 to 637 |
| 637 | Correct | Found in 10 guesses |
2 to the power of 10 is 1,024, just above 1,000. That is why 10 guesses are always enough, and why the Daily Challenge uses this range.
Learn more
The idea behind it
The halving method is called binary search, and it is one of the first algorithms taught in computer science. See it explained step by step on the binary search game page.
More ways to play
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FAQ
Questions
What is the best first guess for 1 to 1,000?
500, the middle. Then 250 or 750 depending on the answer.
How many guesses do you need for 1 to 1,000?
At most 10 with perfect play, because 2 to the power of 10 is 1,024.
Is there a daily version?
Yes. The Daily Challenge uses 1 to 1,000, everyone gets the same number each day, and scores go on a global leaderboard.