1. Mrs. Ennis Estimating Products Lesson Ten
Math Grade 4
Mrs. Ennis
Estimating Products
Lesson Ten

2. 10, =
1,287 – 748 =
8 x 15 =
7 x 7 =
12 ÷ 6 =
3 ½ pounds = _____ ounces

3. At what time after 1:00 and before 2:00 do the hands of a clock form an obtuse angle?
8. 8, =

4. 9. Cecil earns 50 cents for doing shores each day of the week
9. Cecil earns 50 cents for doing shores each day of the week. How much does he earn in 7 days?
10. Ten alligators went down to the river. Three of them laid 5 eggs each. A snake ate 8 of the eggs. How many eggs are left?

6. Estimating Products

7. Steps:
Round multi-digit factors to the greatest place value.
Multiply the front end digits of the rounded number.
Count your zeros in the factors, and add them to the product.

8. Examples
Round multi-digit factors to the greatest place value.
46 x 5 = ? 50 x 5 = ? 5 x 5 =
2) Multiply the front end digits of the rounded number.
3) Count your zeros in the factors, and add them to the product.

9. Examples
Round multi-digit factors to the greatest place value.
32 x 7 = ? 30 x 7 = ? 3 x 7 =
2) Multiply the front end digits of the rounded number.
3) Count your zeros in the factors, and add them to the product.

10. Examples
Round multi-digit factors to the greatest place value.
695 x 4 = ? 700 x 4 = ? 7 x 4 =
2) Multiply the front end digits of the rounded number.
3) Count your zeros in the factors, and add them to the product.

11. Examples
Round multi-digit factors to the greatest place value.
327 x 9 = ? 300 x 9 = ? 3 x 9 =
2) Multiply the front end digits of the rounded number.
3) Count your zeros in the factors, and add them to the product.

12. Examples
Round multi-digit factors to the greatest place value.
1923 x 6 = ? 2000 x 6 = ? 2 x 6 =
2) Multiply the front end digits of the rounded number.
3) Count your zeros in the factors, and add them to the product.

13. Examples
Round multi-digit factors to the greatest place value.
47 x 63 = ? 50 x 60 = ? 5 x 6 =
2) Multiply the front end digits of the rounded number.
3) Count your zeros in the factors, and add them to the product.

14. Examples
Round multi-digit factors to the greatest place value.
613 x 31 = ? 600 x 30 = ? 6 x 3 =
2) Multiply the front end digits of the rounded number.
3) Count your zeros in the factors, and add them to the product.

15. 58 people are invited to the party; you are going to buy supplies
58 people are invited to the party; you are going to buy supplies.  You figure that for each person you need 2 cups, 2 plates, and 3 napkins. Approximately, how many cups, plates, and napkins do you need?
(cups) 58 x 2 =
(plates) 58 x 2 =
(napkins) 58 x 3 =
(cups) 60 x 2 =
(plates) 60 x 2 =
(napkins) 60 x 3 =

16. (cups) 60 x 2 = 120
(plates) 60 x 2 = 120
(napkins) 60 x 3 = 180

17. A can of beans costs $0. 29. A bag of lentils costs $0. 42
A can of beans costs $0.29.  A bag of lentils costs $0.42.  Estimate which is cheaper: to buy 8 cans of beans or to buy 5 bags of lentils.
(beans) $0.29 x 8
(lentils) $0.42 x 5
(beans) $0.30 x 8
(lentils) $0.40 x 5

18. (beans) $0.30 x 8 = $2.40 (lentils) $0.40 x 5 = $2.00
The beans cost more than the lentils.

19. Online Practice

20. Math Fun
Gary began peeling a pile of 44 potatoes at the rate of 3 per minute. Four minutes later, Cam joined him, and peeled at the rate of 5 potatoes per minute. When they were finished, how many potatoes had each peeled?

21. Answer:
Gary: 24 Christen: 20

22. Resources: