Make 88 with four 9s

The classic four nines puzzle: build an expression from exactly four 9s that equals 88. 88 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 88 — the solver checked every possible expression.

Solutions with concatenation and decimals

Concatenation and decimals do not help for 88 either — every combination was checked.

Solutions with square roots, factorials, exponents

(sqrt(9)!! - 9) / 9 + 9 = 88
9 - (9 - sqrt(9)!!) / 9 = 88

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

Make 87 with four 9s · Make 89 with four 9s

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