Four Fours/78/Solutions/2
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Puzzle: Four Fours: $78$
Using exactly $4$ instances of the number $4$, the task is to write an expression for $78$, using whatever arithmetical operations you consider necessary.
Solution
- $78 = \dfrac {4! + 4! \times {. \dot 4} } {\sqrt {. \dot 4} }$
Sources
- 1980: Angela Dunn: Mathematical Bafflers (revised ed.) ... (previous) ... (next): $1$. Say it with Letters: Algebraic Amusements: Four Fours