I just plain got it wrong because of the int @C, after focusing too much on confirming the 21 * 0.5 calculation. Good question in that it highlights rookie mistakes I shouldn't be making....
Thanks,
webrunner
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A SQL query walks into a bar and sees two tables. He walks up to them and asks, "Can I join you?"
Ref.: http://tkyte.blogspot.com/2009/02/sql-joke.html