Four Fours/Lemmata/Three Fours/15

Puzzle

Using exactly $3$ instances of the number $4$, the task is to write an expression for $15$, using whatever arithmetical operations you consider necessary.

Solutions

Solution $1$

$15 = \dfrac {4 + \sqrt 4} {.4}$

Solution $2$

$15 = \dfrac 4 {.4 \times \sqrt {. \dot 4} }$

Also see

Previous  ... Next