It’s time for some number fun with Numberblocks One to Twenty. These colorful, self-correcting puzzles help children practice math skills. This combo pack includes 3 puzzle sets: Counting, Adding & Subtracting, and Sequencing. Counting includes 20 self-correcting 3- piece puzzles featuring Numberblocks One to Twenty. Adding & Subtracting includes 20 colorful, 2-piece puzzles featuring Numberblocks One to Ten. Sequencing includes 10 self-correcting puzzles featuring Numberblocks One through Twenty!