So let's say the problem is 5 - 3, to keep it simple. The answer is 2. To use addition to check you would add 2 + 3 = 5. You can add the smaller numbers to get the one larger number. You can also do it with multiplication and division. For example, 5 * 3 = 15. You can divide 3 by 15 and get 5 or do 5 by15 and get 3.
