Make 1 with four 9s

The classic four nines puzzle: build an expression from exactly four 9s that equals 1. 1 can be made with nothing but four 9s, + - × ÷, and parentheses.

Solutions using only + - × ÷

9 × 9 / 9 / 9 = 1
9 + 9 / 9 - 9 = 1
9 - 9 + 9 / 9 = 1
9 / 9 × 9 / 9 = 1
(9 + 9 - 9) / 9 = 1

…and 11 more at this tier.

Solutions with concatenation and decimals

99 / 99 = 1
.99 / .99 = 1
9.9 / 9.9 = 1
.9 × 9 / .9 / 9 = 1
.9 × 9 / 9 / .9 = 1

…and 82 more at this tier.

Solutions with square roots, factorials, exponents

9 ^ 9 / 9 ^ 9 = 1
(99 - 99)! = 1
99 ^ (9 - 9) = 1
.99 ^ (9 - 9) = 1
.9 ^ 9 / .9 ^ 9 = 1

…and 13865 more at this tier.

13973 distinct solutions found in total, after removing trivial rearrangements.

Make 2 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.