with the .product.properties

To check the version of weblogic, you can open the file In the directory MiddelwareHome\wlserver_10.3\.product.properties and verify the property WLS_PRODUCT_VERSION.

$ cat $FMW_HOME/wlserver_10.3/.product.properties|grep WLS_PRODUCT

WLS_PRODUCT_VERSION=10.3.6.0

with the weblogic console

with the console:

with the weblogic domain general information

with WLST

By checking the version WLST variable

wls:/bifoundation_domain/serverConfig> print version

WebLogic Server 10.3.6.0  Tue Nov 15 08:52:36 PST 2011 1441050