The 24 game has been a beloved mental-math puzzle in classrooms around the world ever since Robert Sun created it in 1988. The rule is very simple — given four numbers, use addition, subtraction, multiplication, division, and parentheses however you like to make the result exactly 24. It looks simple, but actually solving it takes real mental effort, which is exactly why it's popular enough to have inspired competitions in American elementary schools.
Why 24, of all numbers? 24 has an unusually large number of divisors — 1, 2, 3, 4, 6, 8, 12, 24 (exactly 8 of them). Having so many divisors means there are that many more paths to reach it through multiplication and division, which makes the puzzle solvable more often, with more possible answers, than with most other target numbers. That's exactly why 24 was chosen — it hits a sweet spot of being appropriately hard and appropriately solvable.
Getting good at this game takes a few specific instincts. First, it helps enormously to be able to instantly recall the multiplication combos that make 24 (3×8, 4×6, 2×12, 1×24). Another useful strategy is to "compute two of the numbers first to turn them into something easier to work with." For example, given 8, 3, 3, 1, you might subtract 1 from 3 to get 2, make 8×3=24, then divide by that 2… wait, that doesn't work out. This kind of trial and error is itself great practice for building a feel for the four operations.
Part of the charm of this game is that the same four numbers often have more than one answer. Take 4, 4, 4, 4, for instance — there are several different ways to make 24 from it. Just asking yourself "is there another way?" after solving one puzzle doubles the thinking practice you get. On the flip side, some combinations — like 1, 1, 1, 1 — can't make 24 no matter how you arrange them, and running into a case like that and wondering "why doesn't this work?" is a meaningful experience in its own right.
This game is also frequently used in classrooms. It's a perfect tool for students who've just learned order of operations (parentheses first, then multiplication/division before addition/subtraction) to build practical, hands-on fluency. It's often played competitively too, with several people racing to be first to make 24 from the same set of cards — and adding that competitive element makes it a lot more engaging.
On our activity page, you can drag operation symbols into the gaps between four numbers to try to make 24. Tap a filled gap again to clear the symbol, so you're free to try as many times as you like, and if you get stuck, the hint button will show you one working method. Try swapping symbols yourself to explore whether there might be another way, too.