Ghost Mystery Picture: Adding & subtracting to 30

A friendly little ghost with a surprised round mouth, rosy cheeks and a wavy hem. It looks more cute than spooky, so it suits even children who don't like scary things.

Children add and subtract with numbers up to 30 and cross ten along the way: 17 + 6, 26 − 8, 19 + 5, 30 − 12. Since every answer has to match a row on the grid, results never go past the height of the picture, and the bigger numbers appear mostly as the starting number in a subtraction, such as 27 − 9 or 24 − 7. That makes this topic particularly strong on subtracting across a ten from the twenties, which many children find harder than adding.