Subtracting Fractions with Unlike Denominators
Least Common Denominator
Factors Review
Review
100

1/4 + 2/3 =

11/12

100

4/5 - 1/3 =

7/15

100

1/2 and 3/5

LCD: 10

100

List the factors of 18

1, 2, 3, 6, 9, 18

100

What is 5/30 in simplest form?

1/6

200

4/9 + 1/6 =

11/18

200

4/3 - 2/7 =

22/21 or 1 1/21

200

5/12 and 2/9

LCD: 36

200

List the factors of 30

1, 2, 3, 5, 6, 10, 15, 30

200

Estimate this fraction using benchmark fractions.

7/9

300

3/4 + 1/9 =

31/36

300

3/4 - 1/9 =

23/36

300

1/7 and 4/8

LCD: 56

300

List the factors of 21

1, 3, 7, 21

300

Find the sum. Use benchmark fractions to estimate.

2/5 + 6/7

1/2 + 1 = 1  1/2

400

1/2 + 1/3 =

5/6

400

6/7 - 1/2 =

5/14

400

9/10 and 5/6

LCD: 30

400

List the factors of 9

1, 3, 9

400

Estimate the difference using benchmark fractions.

4/8 - 1/5 =

1/2 - 0 = 1/2

500

1/4 + 3/7 =

19/28

500

9/10 - 1/4 =

13/20

500

1/4 and 2/3

LCD: 12

500

List the factors of 8

1, 2, 4, 8

500

What are all the prime numbers between 1-20?

There are 8 prime numbers between 1-20.

2,3,5,7,11,13,17,19

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