These are the rest of the Subtraction facts that the Common Core suggests that students be able to compute mentally such as 18-15, 15-5, and 19-8. 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. 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. To the left 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.