The game of boxes is a great way to practice addition! In this game you keep placing consecutive numbers into the boxes until you get stuck. The game's one rule: you cannot place a number in a box if the box already contains two numbers that add up to it. For instance, you cannot place a 10 in a box containing a 4 and a 6, or place a 7 in a box containing a 2 and a 5. How high can you get?