burger fun / Four Nines / Solver
Make 69 with four 9s
The classic four nines puzzle: build an expression from exactly four 9s that equals 69. 69 cannot be made with + - × ÷, concatenation, or decimals (the solver checked every expression) — solutions need square roots, factorials, or exponents.
Solutions using only + - × ÷
No expression made of four plain 9s and + - × ÷ reaches 69 — the solver checked every possible expression.
Solutions with concatenation and decimals
Concatenation and decimals do not help for 69 either — every combination was checked.
Solutions with square roots, factorials, exponents
9 × 9 - 9 - sqrt(9) = 699 × 9 - sqrt(9) - 9 = 699 × 9 - (9 + sqrt(9)) = 699 + 9 × sqrt(9)! / .9 = 699 + 9 / .9 × sqrt(9)! = 69
…and 29 more at this tier.
34 distinct solutions found in total, after removing trivial rearrangements.
Make 68 with four 9s · Make 70 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.