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 = 5
  • 4 + 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.

Read up on the 1881 original, pick another number in the solver, or find more free math games.