I have been hunting around the web for the decimal representation of the SPBasePermission enum values on more than one occasion for permissions stuff. Usually finding a good resource surf up on Google et al is a bit tough.
So I am bookmarking James’s blog post on it
http://www.jamestsai.net/Blog/post/Understand-SharePoint-Permissions-Part-1-SPBasePermissions-in-Hex2c-Decimal-and-Binary-The-Basics.aspx