Question 474907
Count the numbers in the set {-8000, -7996, -7992, ..., 8000}. Obviously we are not going to do this by hand so what we can do is make transformations to the set by adding 8004 to each element:


|{-8000, -7996, ..., 8000}| = |{4, 8, ..., 16004}| (here |S| denotes the number of elements in set S).


We can divide everything by 4.


|{4, 8, ..., 16004}| = |{1, 2, ..., 4001}|


There are 4001 numbers between -8000 and 8000 inclusive that are divisible by 4.