Objective
The computer has picked a secret whole number from 1 to N. Find it with as few remainder queries as you can. You may also guess the number directly.
Remainders and modular arithmetic
When you divide one whole number by another, the leftover is the remainder. We write this as n mod d (or n % d). For example, 17 divided by 5 is 3 remainder 2, because 5 × 3 = 15 and 17 − 15 = 2. So 17 mod 5 = 2.
If the secret leaves remainder 2 when divided by 5, every remaining candidate must also leave remainder 2. Numbers that do not are crossed off.
Queries and guesses
- Enter a divisor d of 2 or more, then tap Query. You are told secret mod d.
- Each divisor query counts. Fewer queries score better.
- A direct guess that is wrong also counts as a query and rules that number out.
- You win by guessing the secret, or by guessing the last remaining candidate to confirm it.
Difficulty
- Easy: 1 to 40
- Classic: 1 to 70
- Hard: 1 to 100
Daily challenge
Everyone receives the same seeded secret from 1 to 100. It resets at midnight UK. The first solve of the day counts for the league and your streak.