burger fun / Four Fours / Solver
Make 5 with four 4s
The classic four fours puzzle: build an expression from exactly four 4s that equals 5. 5 can be made with nothing but four 4s, + - × ÷, and parentheses.
Solutions using only + - × ÷
(4 + 4 × 4) / 4 = 5
Solutions with concatenation and decimals
(4 + 4) / .4 / 4 = 5(4 + 4) / 4 / .4 = 5(4 - .4) / .4 - 4 = 5(.4 + .4 × 4) / .4 = 5(4 + 4) / (.4 × 4) = 5
…and 2 more at this tier.
Solutions with square roots, factorials, exponents
4! / 4 - 4 / 4 = 5(4 / 4) ^ 4 + 4 = 5(44 - 4!) / 4 = 54 + 4 ^ (4 - 4) = 5(4 - 4)! ^ 4 + 4 = 5
…and 1397 more at this tier.
1410 distinct solutions found in total, after removing trivial rearrangements.
Make 4 with four 4s · Make 6 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.