Make 55 with four 4s

The classic four fours puzzle: build an expression from exactly four 4s that equals 55. 55 cannot be made with + - × ÷ alone (the solver checked every expression) — you will need to stick 4s together (like 44) or use decimals (like .4).

Solutions using only + - × ÷

No expression made of four plain 4s and + - × ÷ reaches 55 — the solver checked every possible expression.

Solutions with concatenation and decimals

44 / (.4 + .4) = 55

Solutions with square roots, factorials, exponents

(4! - .4) / .4 - 4 = 55
44 / .4 / sqrt(4) = 55
44 / sqrt(4) / .4 = 55
44 / (.4 × sqrt(4)) = 55
4! / .4 - sqrt(4) / .4 = 55

…and 33 more at this tier.

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

Make 54 with four 4s · Make 56 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

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