Subtraction is taking away one number from another. Lilly has 4 balloons, but then one flys away. How many does she have left? You can use subtraction to find the answer. First there were 4 balloons.

Ever dreamt of solving math problems in your head with the speed of a calculator? Mental math might seem challenging, but it's a skill attainable through the right tools and techniques. The abacus, an ...