Gamma Function of One Half

Theorem
Let $\Gamma$ denote the Gamma function.

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

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