it should display the version number... as in 10.0.41.
This is based on two things
file:
WEBSITE FILE ROOT \CMS\App_Data\Install\Hotfix.txt
Database:
select KeyName, KeyValue from CMS_SettingsKey where KeyName in
('CMSHotfixVersion', 'CMSDataVersion', 'CMSDBVersion')
results:
CMSDataVersion 10.0
CMSDBVersion 10.0
CMSHotfixVersion 51
If this somehow mismatches you might have an other issue. The value displayed in the admin shows the DB value of CMSHotfixVersion.