1. Topic 7 Estimating Decimal Products and Quotients
5th Grade Math Enrichment
Mrs. Fillat

2. Lesson Objectives By the end of today’s lesson you will be able to:
Estimate products using mental math.
Estimate quotients using compatible numbers.

3. Estimating Products
Estimate each product. 1) 7.65 × 3.2 2) 6.43 × 4.7

4. Estimating Products
Estimate each product. 3) 4.56×7.02 4) 6.3×9.2 5) 3.29×58 ≈ 35 ≈ 54 ≈180

5. Estimating Products
Josh bought 3 yards of fabric to make a flag. Fabric costs $5.35 per yard. The clerk says his total is $14.95 before tax. Did the clerk make a mistake?

6. Estimating Products
You buy 24 donuts from the Donut Emporium in Plano. Each donut costs $.98 . Estimate the cost before tax for 2 dozen donuts? ≈ $24

7. Objective #1
Can you… ~ estimate products using mental math? Let’s Check…

8. Check for Understanding

9. Estimating Quotients
6 ÷ 3 = 2 The first number is the dividend. The second number is the divisor. The number after the = sign is the quotient.

10. Estimating Quotients
Name the following: 18 ÷3 = 6 3 is the: 18 is the: 6 is the:

11. Estimating Quotients
defn: compatible numbers: -numbers easy to divide mentally *When dividing, you can use compatible numbers to estimate quotients

12. Estimating Quotients When you estimate the quotient:
Round the divisor.
Round the dividend to a compatible number.

13. Estimating Quotients
Estimate the quotient using compatible numbers. 1) 14.9 ÷ 2.8 2) 25.3 ÷ 4.9

14. Estimating Quotients
Estimate the quotient using compatible numbers. 3) 35.8÷3.8 4) 29.4÷1.8 5) 49.6÷4.4 ≈ 9 ≈ 15 ≈ 10

15. Estimating Quotients
The cost to ship 1 yearbook is $3.12. The total cost for a shipment was $ Estimate how many books were in the shipment.
Round the divisor.
Round to a multiple of 3.
Find the quotient.

16. Estimating Quotients
Use estimation. Is each quotient reasonable? 1) ÷8.34 =2.15 2) ÷5.94=3.29

17. Estimating Quotients
Use estimation. Is each quotient reasonable? 3) ÷4.07=78.2 4) 41.09÷6.88=5.12 Reasonable Not Reasonable

18. Objective #2
Can you… ~ estimate quotients using compatible numbers? Let’s Check…

19. Check for Understanding
Next, compare answers with a neighbor. 18) ≈5 19) ≈6 21) ≈15

20. Estimating Decimal Products and Quotients
Ask yourself if you can do the following:
Estimate products using mental math.
Estimate quotients using compatible numbers.