Optional Math Challenge: Due 2/23

https://drive.google.com/file/d/0B8-gXqit3js-LUY0OUtGNHl1SXRwTDlrQ3lHc0tzZnlBLVhv/view?usp=sharing

There are 19 students in your classroom. On Valentine's Day, every student gives a valentine to each of the other students. How many valentines are exchanged?