Query the PowerShell Version You're Running

$PSVersionTable

Name                           Value                                                                                 
----                           -----                                                                                 
PSVersion                      5.1.17134.590                                                                         
PSEdition                      Desktop                                                                               
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}                                                               
BuildVersion                   10.0.17134.590                                                                        
CLRVersion                     4.0.30319.42000                                                                       
WSManStackVersion              3.0                                                                                   
PSRemotingProtocolVersion      2.3                                                                                   
SerializationVersion           1.1.0.1


$PSVersionTable.PSVersion

Major  Minor  Build  Revision
-----  -----  -----  --------
5      1      17134  590 


$PSVersionTable.PSVersion.Major

5