Implicit conversions

Hi,

I have a Integer column in a table which is basically the datekey,e.g 20101101.
If I want to get only the year and month from this column is it better to use left(datekey,6) OR datekey/100.
The Left would use implicit conversion.
Which would be faster ?

Thanks !

Same cost but datekey/100 uses less cpu time per my test.

My test came up with the same plan in both the cases as well.
So in general, would implicit conversions always be slower ?

Thanks !

Maybe number of rows affected have play here.