Common Multiple: When two or more numbers have the same numbers as their multiples, those multiples are said to be common multiples.
Least Common Multiple (LCM): The least common multiple (LCM) of two or more numbers is the smallest number that is a multiple of those numbers.
What is the LCM of 9 and 12?
The LCM of 9 and 12 is 36 |
LCM of 9 and 12 with Multiples
Find the least common Multiple (LCM) of 9 and 12.
Step 1: List the multiples of all the given numbers.
Multiples of 9
9 x 1 = 9
9 x 2 = 18
9 x 3 = 27
9 x 4 = 36
9 x 5 = 45
9 x 6 = 54
Multiples of 9 are 9, 18, 27, 36, 45, 54…
Multiples of 12
12 x 1 = 12
12 x 2 = 24
12 x 3 = 36
12 x 4 = 48
12 x 5 = 60
12 x 6 = 72
Multiples of 12 are 12, 24, 36, 48, 60, 72…
Step 2: Identify the common multiples of all the given numbers.
Common multiples of 9 and 12 are 36…
Step 3: Write the least common multiple (LCM) of all the given numbers.
Least Common Multiple (LCM) = 36 (the smallest number of the common multiples)
LCM of 9 and 12 by Division Method
2| 9 12
--|---------
2| 9 6
--|---------
3| 9 3
--|---------
3| 3 1
--|---------
| 1 1
Least Common Multiple (LCM) = 2 x 2 x 3 x 3
LCM = 36
LCM of 9 and 12 by Prime Factorisation Method
Step 1: Find the prime factorization of 9
3| 9
--|----
3| 3
--|----
| 1
prime factorization of 9 = 3 x 3
Step 2: Find the prime factorization of 12
2| 12
--|-----
2| 6
--|-----
3| 3
--|------
| 1
prime factorization of 12 = 2 x 2 x 3
Multiply each factor the greater number of times it occurs in steps 1 or 2 above to find the LCM
9 = 3 x 3
12 = 2 x 2 x 3
LCM = 2 x 2 x 3 x 3
LCM = 36
Hence, the LCM of 9 and 12 by prime factorization is 36.