21 card game - in its non betting form this can be a great game for kids to practice their mental maths. cool math game 21 on Scratch by xe16genesee. cool math game by xe16genesee. scripts. sprites. See inside. Oh no! We're having. Over Activities that Teach Math Facts, Concepts, and Thinking Skills In Count Up, players count from 1 to There are thus 21 objects in this game.