For all Exchange versions and build numbers please visit these websites:

http://social.technet.microsoft.com/wiki/contents/articles/240.exchange-server-and-update-rollups-build-numbers.aspx

For all Exchange 2013 build numbers visit this website :

http://social.technet.microsoft.com/wiki/contents/articles/15776.exchange-server-2013-and-cumulative-updates-cus-build-numbers.aspx

Check the build number by Powershell :

Get-Command Exsetup.exe | ForEach-Object {$_.FileVersionInfo}