Uh, really vague question, but I'm assuming you're asking what the contents of the class are. For any a and b \in Z, the contents will be a + b, for all b. Stated another way, the class will be a + every integer value. So if a = 1.5, [a] will be \{...,-1.5,-.5,.5,1.5,2.5,3.5,4.5,...\}