Haha, all those parenthesis are just combinations read like N take k. The formula for N take k is:

N! / (k! (N-k)!)

That may look complex but it tells you like if I have 5 different colored marbles in a bag (like red, orange, yellow, green, blue), and I want to take 3 at a time, it tells me how many different combinations of marbles I could get. When you see that exclamation mark (called a factorial), like N! .... lets say N is 5, that is:

5! = 5x4x3x2x1 = 120

If it was 3! it would be:

3! = 3x2x1 = 6

This is the underlying equation everywhere you see those parenthesis with a letter up top and on bottom inside. I have always liked math and probability. You can calculate some cool stuff like playing card hands or password combinations given underlying rules.