Make 50 with four 9s

The classic four nines puzzle: build an expression from exactly four 9s that equals 50. 50 cannot be made with + - × ÷, concatenation, or decimals (the solver checked every expression) — solutions need square roots, factorials, or exponents.

Solutions using only + - × ÷

No expression made of four plain 9s and + - × ÷ reaches 50 — the solver checked every possible expression.

Solutions with concatenation and decimals

Concatenation and decimals do not help for 50 either — every combination was checked.

Solutions with square roots, factorials, exponents

(9 × sqrt(9)! - 9) / .9 = 50
(9 + sqrt(9)!) × sqrt(9) / .9 = 50
(9 + sqrt(9)!) / .9 × sqrt(9) = 50
(9 - sqrt(9)! / 9) × sqrt(9)! = 50
9! / 9 / sqrt(9)!! - sqrt(9)! = 50

…and 6 more at this tier.

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

Make 49 with four 9s · Make 51 with four 9s

The Number Lab

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

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Play the daily Four Nines puzzle, pick another number in the solver, or find more free math games.