Make 1 with four 4s

The classic four fours puzzle: build an expression from exactly four 4s that equals 1. 1 can be made with nothing but four 4s, + - × ÷, and parentheses.

Solutions using only + - × ÷

4 × 4 / 4 / 4 = 1
4 + 4 / 4 - 4 = 1
4 - 4 + 4 / 4 = 1
4 / 4 × 4 / 4 = 1
(4 + 4 - 4) / 4 = 1

…and 11 more at this tier.

Solutions with concatenation and decimals

44 / 44 = 1
.44 / .44 = 1
4.4 / 4.4 = 1
.4 × 4 / .4 / 4 = 1
.4 × 4 / 4 / .4 = 1

…and 72 more at this tier.

Solutions with square roots, factorials, exponents

4 ^ 4 / 4 ^ 4 = 1
(44 - 44)! = 1
44 ^ (4 - 4) = 1
.44 ^ (4 - 4) = 1
.4 ^ 4 / .4 ^ 4 = 1

…and 7347 more at this tier.

7445 distinct solutions found in total, after removing trivial rearrangements.

Make 2 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.