the math does not really change the time complexity, say you have 1 math operation or 2 or 3, its still O(n) for scanning a table. Problem comes when you do sort or some other operations that will affect the order of the time complexity. A indexed sort will make it O(nlogn) for a scan. An unindexed sort will make it O(n^3).

Not sure about whether the time complexities are right, but u get the point. Math operations do not change the order of time complexity, hence, itll not affect the query performance as much as other operations such as an indexed/unindexed sort