1. Estimating
Products

2. Use Compatible Numbers…
When estimating fractions you can use 2 different strategies.
Use Compatible Numbers…
…when multiplying a whole number and a fraction.
…when multiplying a mixed number and a fraction. 65 3 x 7 16 3 3 x 5 4

3. Use Compatible Numbers…
When estimating fractions you can use 2 different strategies.
Use Compatible Numbers…
…when multiplying a whole number and a fraction.
…when multiplying a mixed number and a fraction.
Use Rounding…
…when multiplying two mixed numbers.
…when multiplying a mixed number and a whole number. 17 2 4 9 x 65 7 3 10 x 7 5 2 x 1 16 3 3 x 2 5 4

4. Whole Number X Fraction
When to Use What...
Type of Problem
Example
Best Strategy
Whole Number X Fraction 5 6 41 x
Compatible Numbers

5. 41 35 42 ≈ 5 x 6 5 x 6 Estimation with Compatible Numbers 42 ÷ 6 = 7
When estimating a product of a fraction and a whole number, use compatible numbers. 41 35 5 ≈ x 6 42 5
42 ÷ 6 = 7 x
7 x 5 = 35 6
Step 1:
Find the closest basic math fact to 6 and 41.
Step 2:
Rewrite the problem with the compatible numbers.
Step 3:
Divide the whole number by the denominator.
Step 4:
Multiply the quotient by the numerator.

6. Whole Number X Fraction Mixed Number X Fraction
When to Use What...
Type of Problem
Example
Best Strategy
Whole Number X Fraction 5 6 41 x
Compatible Numbers
Mixed Number X Fraction 5 7 x 13 2 9
Compatible Numbers

7. 10 13 14 ≈ x x 2 5 9 7 5 7 Estimation with Compatible Numbers 14 ÷ 7 =
When estimating a product of a fraction and a mixed number, use compatible numbers. 10 13 5 2 ≈ x 7 9 14
14 ÷ 7 = 2 5 x
2 x 5 = 10 7
Step 1:
Find the closest basic math fact to 7 and 13 .
Step 2:
Rewrite the problem with the compatible numbers.
Step 3:
Divide the whole number by the denominator.
Step 4:
Multiply the quotient by the numerator. 2 9

8. 41 13 10 x x x When to Use What... 5 6 5 2 7 9 2 1 3 9 Type of Problem
Example
Best Strategy
Whole Number X Fraction 5 6 41 x
Compatible Numbers
Mixed Number X Fraction 5 7 x 13 2 9
Compatible Numbers
Mixed Number X Mixed Number 10 2 3 x 1 9
Round

9. When estimating a product of mixed numbers, use rounding.
Estimation with
Rounding
Think:
Think: 2 3 1 2 1 9 1 2 V V
Add 1 More!
Just Ignore! 3 10 2 1 x 3 9
When estimating a product of mixed numbers, use rounding. 11 3 33 x =

10. When to Use What...
Type of Problem
Example
Best Strategy
Whole Number X Fraction 5 6 41 x
Compatible Numbers
Mixed Number X Fraction 5 7 x 13 2 9
Compatible Numbers
Mixed Number X Mixed Number 10 2 3 x 1 9
Round
Whole Number X Mixed Number x 4 3 7
Round

11. 7 4 5 7 35 3 x 4 x = Estimation with Rounding V Add 1 More!
Think: 3 4 1 2 V
Add 1 More! 7 4 3 x 4
When estimating a product of a mixed number and a whole number, use rounding. 5 7 35 x =

12. 41 13 10 4 7 x When to Use What... 6 5 2 9 1 3 Best Strategy Example
Type of Problem
Round
Whole Number X Mixed Number
Mixed Number X Mixed Number
Compatible Numbers
Mixed Number X Fraction
Whole Number X Fraction

13. More Examples

14. 32 12 30 ≈ 2 x 5 2 x 5 Estimation with Compatible Numbers 30 ÷ 5 = 6
When estimating a product of a fraction and a whole number, use compatible numbers. 32 12 2 ≈ x 5 30 2
30 ÷ 5 = 6 x
6 x 2 = 12 5
Step 1:
Find the closest basic math fact to 5 and 32.
Step 2:
Rewrite the problem with the compatible numbers.
Step 3:
Divide the whole number by the denominator.
Step 4:
Multiply the quotient by the numerator.

15. When estimating a product of mixed numbers, use rounding.
Estimation with
Rounding
Think:
Think: 3 8 1 2 7 9 1 2 V V
Just Ignore!
Add 1 More! 8 4 3 7 x 8 9
When estimating a product of mixed numbers, use rounding. 8 5 40 x =

16. 41 35 42 ≈ 5 x 6 5 x 6 Estimation with Compatible Numbers 42 ÷ 6 = 7
When estimating a product of a fraction and a whole number, use compatible numbers. 41 35 5 ≈ x 6 42 5
42 ÷ 6 = 7 x
7 x 5 = 35 6
Step 1:
Find the closest basic math fact to 6 and 41.
Step 2:
Rewrite the problem with the compatible numbers.
Step 3:
Divide the whole number by the denominator.
Step 4:
Multiply the quotient by the numerator.

17. Closest Basic Math Fact
Review: Compatible Numbers
Compatible numbers allow you to estimate quotients by changing the dividend and the divisor into a basic math fact.
Division Problem
Closest Basic Math Fact
Estimation
98 ÷ 9
99 ÷ 9 = 11
55 ÷ 8
56 ÷ 8 = 7
29 ÷ 7
28 ÷ 7 = 4
40 ÷ 6
42 ÷ 6 = 7
11 ÷ 3
12 ÷ 3 = 4

18. 7 5 5 8 2 4 3 9 Rounding Fractions V V Find you’re your number,
Look right next door
, just ignore,
or more, add one more.
Think:
Think: 1 2
Less than
Four or less 2 3 4 9 1 2 1 2 V V 1 2
Five
Just Ignore!
Add 1 More! 7 5 5 8 2 4 3 9