Picture yourself as the manager of a sporting goods store. You don't want to run out of best-selling running shoes the week before a marathon, but you also don't want to fill your back room with ski jackets that will sit until winter. On top of that, before you even open a new store, you need to figure out where to put it so enough customers will actually show up. This chapter is about two toolkits that help you solve both puzzles: inventory math and location science.