BiNomial Distribution Formula

My question is in regards to the binomial distribution formula:

Here is the formula...

http://img57.imageshack.us/img57/8378/bdey9.png

it seems to work perfectly when finiding the probability of Exactly 10 customers.

The problem I am having is I can use online Binomial calculators and get the answer.. but i was wondering what formula to use if you are trying to find the probability of for example X > 1 , X < 3

stuff where its not exactly X = 10 or X = 1....

Any help would be greatly appreciated.

THANKS in advance.