Examples
7272 , 454 , 613
Step 1
To find the LCM for a list of fractions such as LCM(ab,cd) using GCF:
1. Find the LCM of a and c.
2. Find the GCF of b and d.
3. LCM(ab,cd)=LCM(a,c)GCF(b,d).
Step 2
Step 2.1
The LCM is the smallest positive number that all of the numbers divide into evenly.
1. List the prime factors of each number.
2. Multiply each factor the greatest number of times it occurs in either number.
Step 2.2
Since 7 has no factors besides 1 and 7.
7 is a prime number
Step 2.3
The prime factors for 45 are 3⋅3⋅5.
Step 2.3.1
45 has factors of 3 and 15.
3⋅15
Step 2.3.2
15 has factors of 3 and 5.
3⋅3⋅5
3⋅3⋅5
Step 2.4
6 has factors of 2 and 3.
2⋅3
Step 2.5
The LCM of 7,45,6 is the result of multiplying all prime factors the greatest number of times they occur in either number.
2⋅3⋅3⋅5⋅7
Step 2.6
Multiply 2⋅3⋅3⋅5⋅7.
Step 2.6.1
Multiply 2 by 3.
6⋅3⋅5⋅7
Step 2.6.2
Multiply 6 by 3.
18⋅5⋅7
Step 2.6.3
Multiply 18 by 5.
90⋅7
Step 2.6.4
Multiply 90 by 7.
630
630
630
Step 3
Find the GCF of the denominators 2,4,13.
GCF(2,4,13)=1
Step 4
Divide 630 by 1.
630