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Subtraction Strategies
**It is critical that students know how to count backwards from 18 to 0, since 18 is the highest number a student will ever have to count backwards from.

If having difficulty, have them use a number line as a visual at first.
Use a number line and count back:

                        12 – 9 = ?  start at the 12 and count back 9

 

         ß--------------------------------------------------------------------------------------------à     

                                0     1    2    3     4    5     6    7    8    9    10     11     12    13    14    15     16     17    18

 

 Website with subtraction strategies (<--click on me)

Count Back (<--click on me)
Use Addition to Subtract (<--click on me)

Use the count on strategy if the difference is small.  For example:

12 – 9 =  à Think 9 and count on to 12

Build up through 10 strategy if one of the digits in the subtraction fact is 8 or 9:

11 -  8 = à  8 plus 2 is ten +1 = 11 so the answer is 3