Perfect for schools and nurserys! They learn, memorise and self-check the addition and subtraction facts for number 1-10. Addition- The sum of the two bottom numbers equals the number at the top of the triangle. Subtraction- Start with the number at the top. Choose a number at the bottom to subtract. Cover the selected number. The answer will be the remaining bottom number. Use a dry erase pen to complete the revision exercises on the back of each laminated card. Combinations can be practised repeatedly. There are 35 cards measuring 13.5cm x 13.5cm. Supplied in an attractive and practical storage container.