Make 24 — The 24 Math Game Online
Four numbers, + − × ÷, one target: 24.
- Mental math
- 4 min
- Medium
Make 24 is the classic 24 puzzle in your browser. You get four numbers. Combine two of them with addition, subtraction, multiplication or division, and they become one card with the result. Keep going until one card is left: if it reads 24, the puzzle is solved. Each number is used exactly once. The first puzzles have many solutions and numbers up to 9; later ones go up to 13 and have only one way in, and the last three can only be solved through a fraction, the way 8 ÷ (3 − 8 ÷ 3) solves 3 3 8 8. You have 3 lives and 20 puzzles.
Play Make 24Difficulty map
From level 1 to the final stop. Percentages come from real HumanCalc players.
- Stop 1 of 20, Easy: puzzle 1.
- Stop 2 of 20, Easy: puzzle 2.
- Stop 3 of 20, Easy: puzzle 3.
- Stop 4 of 20, Easy: puzzle 4.
- Stop 5 of 20, Easy: puzzle 5.
- Stop 6 of 20, Easy: puzzle 6.
- Stop 7 of 20, Medium: puzzle 7.
- Stop 8 of 20, Medium: puzzle 8.
- Stop 9 of 20, Medium: puzzle 9.
- Stop 10 of 20, Medium: puzzle 10.
- Stop 11 of 20, Medium: puzzle 11.
- Stop 12 of 20, Medium: puzzle 12.
- Stop 13 of 20, Medium: puzzle 13.
- Stop 14 of 20, Medium: puzzle 14.
- Stop 15 of 20, Hard: puzzle 15.
- Stop 16 of 20, Hard: puzzle 16.
- Stop 17 of 20, Hard: puzzle 17.
- Stop 18 of 20, Hard: puzzle 18.
- Stop 19 of 20, Hard: puzzle 19.
- Stop 20 of 20, Hard: puzzle 20.
Easy
1–6
Medium
7–14
Hard
15–20
How it works
1You get four numbers and the four operations.
2Tap a number, an operation and another number. They merge into one card, fractions included.
3One card left and it reads 24: solved. Undo is free; a skip costs a life.
How to play
- 1
Pick two numbers and an operation
Tap a number, then +, −, × or ÷, then a second number. The two cards merge into one card that shows the result. Division can give a fraction such as 8/3; it is a card like any other.
- 2
Keep combining until one card is left
Three merges turn four cards into one. If the last card reads 24, the puzzle is solved and the next one appears. If it reads something else, undo a step or start the puzzle over; neither costs anything.
- 3
Beat the clock
The first puzzle has 60 seconds and the time shrinks to 40 seconds by level 11; the fraction puzzles at the end get 50. Running out of time or skipping costs one of your 3 lives and shows one way to solve it.
What it trains
Compute fast without writing anything down. Solving a 24 puzzle means holding several partial results in mind while you test combinations, which is the kind of arithmetic that leans on working memory. DeStefano and LeFevre (2004) reviewed studies showing that mental arithmetic slows down and makes more errors when working memory is loaded. HumanCalc's puzzles come from all 1362 solvable sets of four numbers from 1 to 13, of which 16 can only be solved through a fraction. A score here describes this game, not a clinical measure.
- Practice focus
- Mental math
- Based on
- DeStefano & LeFevre, 2004
Research background
These sources describe related tasks or concepts. HumanCalc adapts them for browser practice; a game score is not a clinical result.
Leaderboard
Resets every Monday 00:00 UTC. The overall weekly top 3 earn a medal and +500 / +300 / +150 XP. How scores work. Scores here show as 5 solved.
Leaderboard
Questions
Can every set of four numbers make 24?
No. Of the 1,820 different sets of four numbers from 1 to 13, 1362 can make 24. HumanCalc only deals sets that have at least one solution.
What are the hardest 24 puzzles?
The ones that need a fraction along the way. 3 3 8 8 is the best known: 8 ÷ (3 − 8 ÷ 3) = 24, because 3 − 8/3 is 1/3. Others are 1 5 5 5, 3 3 7 7 and 4 4 7 7. These make up the last three levels.
Can I use a number twice or skip one?
No. Every number is used exactly once. Once two cards merge, their result replaces them, so the rule takes care of itself.
Are powers, roots or joining digits allowed?
No. Only addition, subtraction, multiplication and division, in any order and with any grouping. Joining 1 and 2 into 12 is not allowed.
What counts as my score?
The number of puzzles you solved, out of 20. A skipped or timed-out puzzle does not count, and you get a new set at the same level.
Any tips for getting faster?
Look for the factor pairs of 24 first: 3 × 8, 4 × 6, 2 × 12. If you can make one half of a pair from two numbers, try to make the other half from the rest. When nothing whole works, look for a division that leaves a fraction you can cancel later.
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