burger fun / Four Nines / Solver

Make 19 with four 9s

The classic four nines puzzle: build an expression from exactly four 9s that equals 19. 19 can be made with nothing but four 9s, + - × ÷, and parentheses.

Solutions using only + - × ÷

• 9 + 9 + 9 / 9 = 19

Solutions with concatenation and decimals

• .9 / .9 + 9 + 9 = 19
• (.9 × 9 + 9) / .9 = 19
• (9 + 9 - .9) / .9 = 19
• (9 - (.9 - 9)) / .9 = 19

Solutions with square roots, factorials, exponents

• 9! / 9! + 9 + 9 = 19
• 9 + 9 + 9! / 9! = 19
• (9 - 9)! + 9 + 9 = 19
• (.9 - .9)! + 9 + 9 = 19
• (9! - 9!)! + 9 + 9 = 19

…and 35 more at this tier.

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

Make 18 with four 9s · Make 20 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.