Question

Find the GCF and LCM of each number using any of the methods.​

Answer 1

The GCF is the smallest shared prime factor for each term.

The LCM is the smallest whole number that both numbers share as multiples.

For example, take #16.

Factors of 25: 1 , 5, 25

Factors of 75: 1 , 3, 5, 15, 25 ,75

The GCF that is shared would then be 25.

The smallest multiple that both share as multiples:

Multiples of 25: 25, 50, 75, etc.

Multiples of 75: 75, etc.

The LCM that is shared would then be 75.

16) 25 and 75

GCF: 25

LCM: 75

17) 35 and 5

GCF: 5

LCM: 35

18) 27 and 36

GCF: 9

LCM: 108

19) 21 and 56

GCF: 7

LCM: 168

20) 54 and 72

GCF: 18

LCM: 216