What is the common denominator these fractions?

SET 1

Assuming the three compound fractions are

8 11/12, 1 2/15 and 3 6/11

Factor all three denominators into their prime numbers

12 = 1 * 2 * 2 * 3 = 2 * 2 * 3

15 = 1 * 3 * 5 = 3 * 5

11 = 1 * 11 = 11

Next count the number of times each prime appears in each factor.

12 has two 2's and one 3

15 has one 3 and one 5

11 has one 11

For each prime number, list the largest count for each factor.

2 appears a maximum of two times (in number 12)

3 appears a maximum of one time (in number 12 and in number 15)

5 appears a maximum of one time (in number 11)

Multiply these largest counts

2 * 2 * 3 * 5 * 11 = 660

Least Common Denominator = 660

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Follow the solution I provided for set 1 above to solve set 2 and 3 below.

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Assuming the three compound fractions are

3 7/15, 5 6/7 and 1 1/8

Factor all three denominators into their prime numbers

15 = ?

7 = ?

8 = ?

Next count the number of times each prime appears in each factor.

15 has ?

7 has ?

8 has ?

For each prime number, list the largest count for each factor.

2 appears a maximum of ?

3 appears a maximum of ?

5 appears a maximum of ?

7 appears a maximum of ?

Multiply these largest counts

?

Least Common Denominator = ?

HINT: 800 < LCD < 850

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Assuming the three compound fractions are

2 3/20, 7 7/9 and 15 9/17

Factor all three denominators into their prime numbers

20 = ?

9 = ?

17 = ?

Next count the number of times each prime appears in each factor.

20 has ?

9 has ?

17 has ?

For each prime number, list the largest count for each factor.

2 appears a maximum of ?

3 appears a maximum of ?

5 appears a maximum of ?

17 appears a maximum of ?

Multiply these largest counts

?

Least Common Denominator = ?

HINT: 3000 < LCD < 3100

haha if you don't have a calculator you can do this. (Btw this is a very easy question to solve without finding the common denominator, but this wont work for every question) Compare all these fraction to the base fraction 1/2. 5/8 is greater than 1/2, 6/13 is smaller, 9/17 is greater, 10/19 is greater. This means that 6/13 is the only one less than half thus it is the smallest. Now you could go and do it with the lowest common denominator but it would take way too much time. Hope you got it.

looks like you should just multiply all the denominators together, then see if you can simplify from there