How to play
You are dealt four numbers. Using each of them exactly once, and any of the four operations — add, subtract, multiply, divide — make the number 24. Order and brackets are yours to choose. Dealt 4, 6, 7, 8, you might spot (7 − 4) × 8 = 24 — but that leaves the 6 unused, so it does not count. 4 × 6 × (8 − 7) = 24 uses all four, and that is the game: hands look easier than they are.
Tap a card, tap an operation, tap a second card, and the two cards fold into one showing the result. Three merges leave one card; if it reads 24, you have it. A result that is not a whole number is shown as a fraction and stays in play — a few of the hardest hands can only be done that way.
Controls
- Click a card, an operation, then another card — the first card is folded into the second
- 1–4 — pick a card by position
- + - * / — pick an operation
- Esc — clear the selection
- Z, U or Backspace — undo a merge
- H — use a hint (3 per hand; lights up one merge that keeps 24 reachable)
- S — give up and see a solution
- R — restart the hand · N — next hand
Strategy tips
- Know the factor pairs. 24 is 1 × 24, 2 × 12, 3 × 8 and 4 × 6. Most hands are solved by making one number of a pair out of two cards and the other out of the remaining two.
- Aim for 24 ± something. If three cards make 20, 25, 27 or 30, the fourth only has to bridge the gap. Sums like 12 + 12 and 30 − 6 come up constantly.
- Big cards multiply, small cards adjust. A 12 or 13 usually wants to be doubled or have a small number taken off; a 1 is often best used as ×1 or ÷1 at the very end.
- Watch the status line. It tells you the moment the cards on the table can no longer make 24, so you never waste time down a dead end — undo and try the other order.
- Fractions are a tool. When nothing whole works, think about 8 ÷ (something) = 24: the something is a third, and 3 − 8 ÷ 3 is exactly that. The hard bucket is built on tricks like this.
About the 24 Game
The 24 Game has been played with an ordinary deck of cards for as long as anyone remembers — deal four, race to make 24 — and was turned into a boxed set of number cards by Robert Sun in 1988 that went on to be a fixture of American maths classrooms. The target is chosen well: 24 has more divisors than any smaller number, so most hands have a way through.
This edition deals from every hand there is. Four numbers from 1 to 13 can be dealt in 1,820 different ways, and 1,362 of them can make 24; all 1,362 are here, and the 458 that cannot are left out, so every hand you see has an answer. Each hand is solved by the same code that shows you a solution, and graded by how many ways it can be done in whole numbers — from the easy bucket, where there are ten or more, to the hard bucket, where there are two or fewer, including the sixteen hands that cannot be done without a fraction along the way.