Make 99 with four 9s

The classic four nines puzzle: build an expression from exactly four 9s that equals 99. 99 can be made with nothing but four 9s, + - × ÷, and parentheses.

Solutions using only + - × ÷

9 × 9 + 9 + 9 = 99
9 + 9 + 9 × 9 = 99

Solutions with concatenation and decimals

9 × 99 / 9 = 99
9 + 99 - 9 = 99
9 - 9 + 99 = 99
9 / 9 × 99 = 99
99.9 - .9 = 99

…and 22 more at this tier.

Solutions with square roots, factorials, exponents

9! × 99 / 9! = 99
9! + 99 - 9! = 99
9! - 9! + 99 = 99
9! / 9! × 99 = 99
(9 - 9)! × 99 = 99

…and 62 more at this tier.

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

Make 98 with four 9s · Make 100 with four 9s

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

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