Four Fours/13

Puzzle

Using exactly $4$ instances of the number $4$, the task is to write an expression for $13$, using whatever arithmetical operations you consider necessary.

Solutions

Solution $1$

$13 = \dfrac {4!} {\sqrt 4} + \dfrac 4 4$

Solution $2$

$13 = \dfrac {44} 4 + \sqrt 4$

Solution $3$

$13 = \dfrac {4 - .4} {.4} + 4$

Solution $4$

$13 = \map \Gamma 4 \times \sqrt 4 + \dfrac 4 4$

where $\Gamma$ is the gamma function: $\map \Gamma 4 = 6$

Also see

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