Unit 11 Contents

For Questions 11–15, make your own estimate for each problem. Then decide whether the student's estimate is a “could be” or “crazy” estimate. If the estimate seems appropriate, record your answer as “could be.” If the estimate is too high or too low, record your answer as “crazy.” Be ready to explain how you decided.

11. Tanya said, “76 42 is close to 280.”
12. Romesh said, “35 35 is between 900 and 1600. 1200 is my estimate.”
13. Luis said, “The answer to 17 34 is less than 400.”
14. Jessie said, “57 26 is less than 1000.”
15. Shannon said, “A good estimate for 11 55 is 550.”

16. Solve the following problems using the all-partials method. Estimate to be sure your answers are reasonable.
1. 
2. 
3. 
4. 



17. Explain your estimation strategy for Question 16C. Is your exact answer close to your estimate?

Check-In: Question 18

1. Compute 43 27 two ways. Use the all-partials method and either the rectangle or expanded-form method. Estimate to be sure your answer is reasonable.”
2. Compare the two methods. Explain how they are alike. Explain how they are different.

Use the My Multiplication Menu in the Student Activity Book to develop your own multiplication strategy menu for multidigit factors.