1. How can I subtract by using addition? Isn’t addition the opposite of subtraction?

2. In this lesson you will learn how to subtract two 2-digit numbers by using addition.

3. Let’s Review Subtraction: Finding the difference between 2 numbers. We can count back from the larger number… Or, we can count up from the smaller number.

4. Subtraction: Counting Back: 47 - 32 = Counting Up: 15 32 + ? = 47 15

5. Open Number Lines Open number lines can help us add and subtract. I can jump by tens and ones to find the sum or difference of 2 numbers. 17 - 14 1417 = 3

6. A Common Misunderstanding Thinking that the 8 in 87 has a value of 8 instead of 80. 8 07 7 X

7. Core Lesson Subtract 63 - 32 by counting up. When we subtract we want to find the difference between 2 numbers. How many more are needed to get 63 when we add up from 32? 32 + ? = 63

8. An open number line can help us count up! 32 63 ? 42 +10 +10 52 62 +10 +1 63 - 32 = 31 = 31 32 + ? = 63 31

9. Core Lesson Subtract 86 - 27 by counting up. 27 86 ? +3 30 +50 80 +6 How far away is the nearest 10? Can I hop by multiples of 10 on the number line? = 59 27 + ? = 86 59 86 - 27 = 59

10. In this lesson you have learned how to subtract two 2-digit numbers by using addition.