I'm trying to get a percentage of high school graduates from the census data. The numbers are coming out as whole numbers but should be decimals. Is there a trick to doing math in label expressions?

round((([Estimate__Female____High_school_graduate__includes_equivalency_]+ [Estimate__Male____High_school_graduate__includes_equivalency_] )/ [Estimate__Total_] ),2)

Try casting top or bottom as float:

Alternatively, you can use the matrix:

The explanation is that Python 2.x returns an integer for integer/integer, but returns float for float/integer or integer/float.

edit: probably should have led with: what language are you trying to use?

The following VBScript expression returns decimals for me: