Random number between 1 and 100

A random number from 1 to 100

The range is already set to 1 to 100. Click “Pick a number” or press the space bar and you get a whole number chosen by your browser's cryptographic random generator. All hundred numbers have the same chance, and nothing leaves your device.

When to draw between 1 and 100

• A raffle at the school fair or sports club: tickets run from 1 to 100 and the draw happens on screen, in front of everyone. For three prizes, set “How many numbers” to 3 and tick “No duplicates”, so no ticket wins twice. Only sold 80 tickets? Lower the maximum to 80.
• A random percentage: for a maths worksheet, a stat in a tabletop game or a test value, the result reads directly as a percentage.

Your odds between 1 and 100

• One specific number: 1 in 100, or 1%.
• An even number: 50 out of 100, or 50%.
• A multiple of 10 (10, 20, 30… 100): 10 out of 100, or 10%.
• A prime number: 25%, because there are 25 primes up to 100, from 2 to 97.

Why 7 guesses are always enough

The trick is to guess the middle of whatever is left. Each answer then removes at least half of the options: at worst 50 remain, then 25, 12, 6, 3 and finally 1. Say the secret number is 83: 50 (higher), 75 (higher), 88 (lower), 81 (higher), 84 (lower), 82 (higher), then 83 on the seventh guess.

Put another way, you have to double seven times to get past 100: 2 to the power of 7 is 128. With only six guesses (2 to the power of 6 is 64), you can't be sure of finding it.

FAQ

Can 100 come up?

Yes, both ends are included. For a draw from 0 to 99, just change the minimum and maximum.

How do I shuffle a list of 100 items?

Ask for 100 numbers and tick “No duplicates”: every number from 1 to 100 comes out once, in random order. The “Copy” button then pastes them one per line, ready for a spreadsheet.