Using the numbers 1 through 9, mathematician Ben Sparks introduces us to the '15-game.' This is a fun strategy game for two players where the goal is to be the first person to pick three numbers that add up to exactly 15. In this episode of Numberphile—which is Brady Haran’s popular video project all about the cool world of numbers and mathematics—Ben explains the game. He shows us that by using special pictures and patterns, we can see the secrets behind the math. Even though it might look like just a simple game at first, there is a lot of clever thinking hidden inside. By visualizing the numbers, you can spot the winning moves more easily!