I first encountered Pascal’s triangle on a worksheet my older brother brought home from school when I was in eighth grade. At the time, I was taking geometry (with a teacher who had a cool pair of ...

Pascal's rule tells us that each entry of Pascal's triangle is the sum of the entry to its upper right and its upper left. For example, 4 choose 2 is equal to 3 choose 1 plus 3 choose 2. Here's ...