Make 15 with four 4s

The classic four fours puzzle: build an expression from exactly four 4s that equals 15. 15 can be made with nothing but four 4s, + - × ÷, and parentheses.

Solutions using only + - × ÷

4 × 4 - 4 / 4 = 15

Solutions with concatenation and decimals

4 + 44 / 4 = 15
4 + 4.4 / .4 = 15
4 × 4 - .4 / .4 = 15
(.4 + 4) / .4 + 4 = 15
(4 / .4 - 4) / .4 = 15

Solutions with square roots, factorials, exponents

4 × 4 - 4! / 4! = 15
4 × 4 - (4 - 4)! = 15
(4 - 4 / 4)! / .4 = 15
(.4 - 4) / .4 + 4! = 15
4! - (4 - .4) / .4 = 15

…and 216 more at this tier.

227 distinct solutions found in total, after removing trivial rearrangements.

How 15 compares

15 has 227 distinct solutions across all three tiers — #29 most plentiful of the 95 solvable targets. Exactly one of them uses nothing but + - × ÷. Next door, 14 has 327 solutions and 16 has 2,689 solutions. The nearest impossible target is 73, 58 away — proven unreachable, not just unsolved.

If 15 went down easily, make 13 with four 4s — 70 solutions, the nearest step up in scarcity.

Make 14 with four 4s · Make 16 with four 4s

The Number Lab

Same idea, different constraints: four 9s, four 4s, or any four digits you like.

Four Nines — the daily puzzle
Four Nines solver — every target, solved
Four Fours — the 1881 original
Four Fours solver — including the impossible five
Make 24 solver — any four digits
Today's 24 — one new hand a day

Got what you came for?

Stay for something you did not search for.

Four Nines — the daily sibling: four 9s, one target, new at midnight
The Reflex Lab — nine ways to measure your hands and memory, none of them polite about it
hand me something weird — a random pick from the directory. Could be the horse.

Read up on the 1881 original, pick another number in the solver, or find more free math games.