Gamma Function of One Half

Theorem

 * $\map \Gamma {\dfrac 1 2} = \sqrt \pi$

where $\Gamma$ denotes the Gamma function.

Its decimal expansion starts:
 * $\Gamma \left({\dfrac 1 2}\right) = 1 \cdotp 77245 \, 38509 \, 05516 \, 02729 \, 81674 \, 83341 \, 14518 \, 27975 \ldots$