Four Fours/84/Solutions/2

Puzzle: Four Fours: $84$

Using exactly $4$ instances of the number $4$, the task is to write an expression for $84$, using whatever arithmetical operations you consider necessary.

Solution

$84 = \dfrac {4! + 4! \times .4} {.4}$

Sources

• 1980: Angela Dunn: Mathematical Bafflers (revised ed.) ... (previous) ... (next): $1$. Say it with Letters: Algebraic Amusements: Four Fours