Sigma

Sigma is the greek symbol. It is used to find the sum of numbers between x and y. In its simplest form, it is something like: 15, which is equivalent to: 1 + 2 + 3 + 4 + 5 It can also be used in a context in which x is not equal to 1, such as: 48, which is equivalent to: 4 + 5 + 6 + 7 + 8 18 - 13 = = = = =The Equation for Sigma is:= =__y^2 + y__ __ysq +__y= y =2= Another equation is:

__**y (y+1)**__ this is why:
 * 2**

==Sigma can also be used to find out the number of hand shakes in a room between x amount of people. **If you want to investigate more about this, see a slightly more obnoxious explanation in Nerdy Handshakes.**== ==To find out what happens when you put Bill Clinton, David Letterman, Stephon Marbury, Jay Leno, Brad Pitt, John Travolta, Barrack Obama, Sidney Crosby, Johnny Depp, George Clooney, Hilary Clinton and Rocky Balboa in a room? Click here to find out.==