Lesson 2-1.1

Lesson 2-1
Fill in the unit box. Complete the fact extensions.
12-7=
120-70=
1,200-700=
8+3=
80+30=
800+300
6 + 8
16 + 8
56 + 8
14-9=
24-9=
54-9=
Explain how you used a basic fact to help you solve Problem 4.
Enter 33 change to 40
Enter 80 change to 73
Enter 80 change to 23
Enter 430 change to 500
Enter 700 change to 640
Enter 1000 change to 400
Add or subtract to complete these problems on your calculator. You may also use a number grid or base-10 blocks.
What combination of 10 helped you solve Problem 6? Explain.
Should be Empty: