Toadstool Mystery Picture: Adding & subtracting to 30

A toadstool with a red cap full of white spots on a pale stem. The spots are the cells left uncolored, so the pattern appears by itself as the cap fills in.

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.