Least Common Multiples through lists
It is possible to find the Least Common Multiple (LCM) of two or more numbers by simply listing the multiples of each number, and circling the ones they all have in common, and then identifying the smallest circled number.
EXAMPLE: To find the Least Common Multiple of 12 and 20
(Remember, LCM is the smallest number that each given number multiplies to)
1st:
12 = 12, 24, 36, 48, 60, 72, 84, 96, 120 …. list the multiples of the first number
20 = 20, 40, 60, 80, 100, 120, 140 …… list the multiples of the second number
LCM =
2nd:
12
= 12, 24, 36, 48, 60, 72, 84, 96, 120
…. Circle any found in both lists
20 = 20, 40, 60, 80, 100, 120, 140…
LCM =
3rd:
12
= 12, 24, 36, 48, 60, 72, 84, 96, 120
…. Select the smallest number circled
20 = 20, 40, 60, 80, 100, 120, 140…
LCM = 60
EXAMPLE
24 = 24, 48, 72, 96, 120, 144, 168, …..
30 = 30, 60, 90,
120, 150………
LCM = 120
Problems
For the numbers given below, find the Greatest Common Factor (GCF) of each group.
1) 2)
12
= 10
=
16
= 8 =
LCM = LCM
=
3) 4)
5 = 6 =
12
= 10 =
LCM
= LCM
=
Problems
For the numbers given below, find the Greatest Common Factor (GCF) of each group.
1) 2)
2 = 12 =
6 = 5 =
LCM LCM
=
3) 4)
20
= 9 =
6 = 8 =
LCM= LCM
=
5) 6)
8 = 10 =
12 = 12 =
LCM= LCM
=
7) 8)
5 = 2 =
8 = 3 =
LCM= LCM
=
9) 10)
12
= 10
=
4 = 6 =
LCM= LCM
=
Find two numbers that have the LCM indicated
11) 12)
= =
= =
LCM = 20 LCM = 12
GCF GCF
=