Free interactive math game: Balance Both Sides — 5 + 7 = ? + 4. 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.
Making two sides of an equation equal — the meaning of the equals sign.
Work out the side that is complete, then find what the other side needs to match it. The equals sign means the same value, not here comes the answer.
In 11 + 2 = ? + 9, the left is 13, so the gap must be 13 - 9 = 4.
Treating the equals sign as an instruction. In this kind of question the answer is rarely the total of the numbers on the left.