Title: Greatest Common Factor and Least Common Multiples GCF and LCM
1Greatest Common Factor and Least Common
MultiplesGCF and LCM
2What is the difference between a factor and a
multiple?
3Give me an example of a factor of 15
4Give me an example of a multiple of 15
5How would you find the GCF of 60 and 96?
6There are actually 2 ways. You can use prime
factorization, or write out all the prime
factors for each number.
7List the factors of 601,2,3,4,5,6,10,12,15,20,3
0,60List the factors of 961,2,3,4,6,8,12,16,24
,32,48,96find the largest factor - 12
8or do prime factorization. Circle all the
primes the 2 numbers have in common and multiply
one set of them to get your GCF.
96
60
48
2
2
30
24
2
15
2
12
2
3
5
6
2
2 x 2 x 3 12
2
3
9Find the GCF (HCF) of 36, 24, 144 and 96
1096
24
36
48
2
2
12
18
2
24
2
6
9
2
2
12
2
3
2
3
3
6
2
144
2
3
12
12
3
4
2 x 2 x 3 12
3
4
2
2
2
2
11There are 2 ways to find the LCM as well. You
can list the multiples of the numbers or do prime
factorization. Find the LCM of 12 and 18
12Multiples of 12 are12,24,36,48,60,72,.Multip
les of 18 are18,36,54,72,90,108,The
smallest multiple the 2 numbers have in common is
the least common multiple.
13or do prime factorization. Write down the
number they have in common only once, then write
down the leftover numbers. Multiply them all
together.
12
18
9
4
2
3
3
3
2
2
Numbers in common are 2 and 3 Leftover numbers
are 2 and 3 2 x 3 x 2 x 3 36
14Find the LCM of 35, 420 and 245
15245
35
420
42
5
49
10
5
7
5
7
7
2
6
7
2
3
Numbers they have in common 5 and 7 Leftover
numbers 2, 3, 2, 7 Multiply them all together
5 x 7 x 2 x 3 x 2 x 7 2940