Four Fours/90/Solutions/3

Puzzle: Four Fours: $90$

Using exactly $4$ instances of the number $4$, the task is to write an expression for $90$, using whatever arithmetical operations you consider necessary.

Solution

$90 = 4 \times 4! - 4 - \sqrt 4$

Sources

• 1964: L.H. Clarke: Fun with Figures ... (previous) ... (next): Solutions: $(46)$