GCF of 45 and 80

Answer 1

Greatest common factor of two numbers x and y(x>y) is always less than or equal to y.

So, we will write down only those factors of 800 which are less than or equal to 45.

Factors of 45: 1, 3, 5, 9, 15 and 45.

Factors of 800: 1, 2, 4, 5, 8, 10, 16, 20, 25, 40...

So, Greatest common factor is 5.

Alternate Method:

Method of prime factorization:

45 = 3x3x5

800 = 2x2x2x2x2x5x5

It is clear that 5 is the only number which divides both 45 and 800.

So, gcf of 45 and 800 is 5.

Answer 2

The GCF is 5.

Answer 3

The GCF is 1.

Answer 4

It is: 5

Answer 5

5.