COUNTING BACK:         any number minus 1, 2, or 3.

                                             (9-3=6, 14-2=12, 13-1=12)

                                             Start at the highest number and count back.

SUBTRACTION DOUBLES:  knowing that subtraction is the opposite of addition. We use addition double facts to solve subtraction facts.

                                                      (8-4=4, 12-6=6, 10-5=5)

ZERO FACTS:         any number minus zero equals that same number

                                    (13-0=13, 9-0=9)

                                    any number minus itself equals zero

                                    (27-27=0, 3-3=0, 5-5=0)

COUNTING UP TO SUBTRACT:   some subtraction facts do not fit into any of the above categories: 10-9=?, 7-6=?

                                                               When numbers are close together and it doesn’t make sense to count back, we count up: 10-7=? (start at the 7, count up to 10, think “8, 9, 10”, your answer is 3.

                                                               This concept is hard for some children to grasp at first.