On a tranquil summer night, the numbers 0, 9, and the other eight digits leap out of their math textbook. Led by a little monkey on a rocking horse, they begin playing all sorts of fun games. At first, 0 always wants to stay close to 9, but whether it's the little monkey or the other numbers, everyone insists that 0 stick with 1, which makes it quite unhappy. When they split into two teams for a size comparison game, 0 becomes the most sought-after player and can't help but feel smug and inflated with pride—even looking down on 9. But after drifting away from the group, it grows lonely and starts to feel sad. Later, 0 realizes that it is just one member of a big collective family, and no matter how strong it may seem on its own, its power is insignificant compared to that of the group. So, it returns to the warm and joyful embrace of the big family. Synopsis from Douban.