Subtract from 20 (e.g., 18-15, 15-5, 19-8)

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Why teach Subtract from 20 facts?

The Common Core suggests that students be able to compute mentally facts such as 18-15, 15-5, and 19-8.  We call these the Subtract from 20 facts. These obviously build on the basic single digit facts such as 8-5, 5-5, and 9-8. Students should find these fairly easy to master but they still need some practice to commit them to memory.

Please give the special Writing Speed Test.

LOOK OUT! Because all the answers are two digits, the number of problems students can be expected to answer will go down!  You must give the special Subtract from 20 Writing Speed Test to set new, lower, goals for your students.  Above you can see the sequence of facts that will be learned in the Subtract from 20 program.  Otherwise, the program is exactly the same as the basic Subtraction Rocket Math program and uses the same forms–that can be found in the forms and information drawer.

 

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