Free interactive math game: 25 + ? = 40 — To 50. Part of the Missing Numbers (Gaps) category on MathKite.
Taken from the generator that powers this exercise. A fresh set appears every time the page is opened, and the printable worksheet holds ten of them.
Adding two numbers, with the answer chosen from a set of options.
Add the ones first, then the tens. When the ones pass ten, carry the extra ten across before finishing.
For 43 + 24, add the ones (3 + 4 = 7) then the tens (40 + 20 = 60), which gives 67.
Forgetting to carry. In 28 + 7 the ones make 15, so the ten inside it has to move up: the answer is 35, not 25.