Four Fours/18/Solutions/2

Puzzle: Four Fours: $18$

Using exactly $4$ instances of the number $4$, the task is to write an expression for $18$, using whatever arithmetical operations you consider necessary.

Solution

$18 = 4 \times 4 + 4 - \sqrt 4$

Sources

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