What is the greatest common factor of 42 56 and 105?

Answer 1

The factors of 42 are: 1, 2, 3, 6, 7, 14, 21, 42

The factors of 81 are: 1, 3, 9, 27, 81

The factors of 105 are: 1, 3, 5, 7, 15, 21, 35, 105

The common factors are: 1, 3

• The Greatest Common Factor (GCF) is: 3

Answer 2

Using Prime factorisation:

42 = 2 x 3 x 7

81 = 3⁴

105 = 3 x 5 x 7

→hcf = 3

→lcm = 2 x 3⁴ x 5 x 7 = 5670

Answer 3

The GCF is 7.

Answer 4

The GCF is 21.

Answer 5

The GCF is 21.

Answer 6

GCF(42, 81, 105) = 3

Answer 7

2835

Answer 8

21 is.