Look at the top number (the target) and one of the bottom numbers (known addend).
Use the number keyboard to fill in the missing addend that makes the number bond complete.
For example: If the top shows 10 and one bottom shows 3, the missing number is 7 (because 3 + 7 = 10).
Click "New Problem" for a new challenge, "Clear" to erase your answer, or "Hint" for help.