What version of git am I running?

use:

git --version

e.g.

> git --version
git version 2.7.0.windows.1

In Powershell, which git will also give you the answer you seek. For example:

> which git

CommandType     Name                                               Version    Source
-----------     ----                                               -------    ------
Application     git.exe                                            2.7.0.0    C:\Program Files\Git\cmd\git.exe