sccm 2012 Cumulative updates version determine

To check the Cumulative updates number , open this  registry key
 HKLM\SOFTWARE\Microsoft\SMS\Setup\CULevel

System Center 2012 Configuration Manager CU1  - 5.00.7711.0200

System Center 2012 Configuration Manager SP1 CU1  - 5.00.7804.1202
System Center 2012 Configuration Manager SP1 CU2  - 5.00.7804.1300
System Center 2012 Configuration Manager SP1 CU3 - 5.00.7804.1400