Count On and Use Ten to Subtract - Up to 20
⚡️ The ultimate combination! Let's put two mighty strategies together to solve any teen subtraction problem in record time.
Do this: Read the concept below, then try the quiz or activity.
Concept
You know how to "Count On", and you know how to use "Ten as a stepping stone". Let's put them together!
🎯 The Combo Strategy: Example: 14 - 8 = ? We can count UP from 8 to 14, but we'll use 10 as a rest stop to make it faster. 1. Count up from the small number to 10: How many steps from 8 to 10? It's 2 steps. 2. Count up from 10 to the big number: How many steps from 10 to 14? It's 4 steps. 3. Add your steps together! 2 steps + 4 steps = 6 total steps. So, 14 - 8 = 6.
This is the fastest mental math trick for hard subtraction problems!
Try it
Let's combo our strategies!
Instructions: Find the steps to 10, then the steps past 10, and add them together.
Problem 1: 15 - 9 = ? * Steps from 9 to 10: 1 * Steps from 10 to 15: 5 * Add them up! 1 + 5 = ___ * Answer: 15 - 9 = ___
Problem 2: 13 - 7 = ? * Steps from 7 to 10: ___ * Steps from 10 to 13: ___ * Add them: ___ + ___ = ___ * Answer: 13 - 7 = ___
Problem 3: 16 - 8 = ? * Answer: ___
Problem 4: 12 - 9 = ? * Answer: ___