How many positive integers less than 72 have the property that the greatest common factor of the number and 72 is equal to 1?

Here are the greatest common factors of the pairs of numbers including 72:

GCF of 1, 72 is 1

GCF of 2, 72 is 2

GCF of 3, 72 is 3

GCF of 4, 72 is 4

GCF of 5, 72 is 1

GCF of 6, 72 is 6

GCF of 7, 72 is 1

GCF of 8, 72 is 8

GCF of 9, 72 is 9

GCF of 10, 72 is 2

GCF of 11, 72 is 1

GCF of 12, 72 is 12

GCF of 13, 72 is 1

GCF of 14, 72 is 2

GCF of 15, 72 is 3

GCF of 16, 72 is 8

GCF of 17, 72 is 1

GCF of 18, 72 is 18

GCF of 19, 72 is 1

GCF of 20, 72 is 4

GCF of 21, 72 is 3

GCF of 22, 72 is 2

GCF of 23, 72 is 1

GCF of 24, 72 is 24

GCF of 25, 72 is 1

GCF of 26, 72 is 2

GCF of 27, 72 is 9

GCF of 28, 72 is 4

GCF of 29, 72 is 1

GCF of 30, 72 is 6

GCF of 31, 72 is 1

GCF of 32, 72 is 8

GCF of 33, 72 is 3

GCF of 34, 72 is 2

GCF of 35, 72 is 1

GCF of 36, 72 is 36

GCF of 37, 72 is 1

GCF of 38, 72 is 2

GCF of 39, 72 is 3

GCF of 40, 72 is 8

GCF of 41, 72 is 1

GCF of 42, 72 is 6

GCF of 43, 72 is 1

GCF of 44, 72 is 4

GCF of 45, 72 is 9

GCF of 46, 72 is 2

GCF of 47, 72 is 1

GCF of 48, 72 is 24

GCF of 49, 72 is 1

GCF of 50, 72 is 2

GCF of 51, 72 is 3

GCF of 52, 72 is 4

GCF of 53, 72 is 1

GCF of 54, 72 is 18

GCF of 55, 72 is 1

GCF of 56, 72 is 8

GCF of 57, 72 is 3

GCF of 58, 72 is 2

GCF of 59, 72 is 1

GCF of 60, 72 is 12

GCF of 61, 72 is 1

GCF of 63, 72 is 9

GCF of 64, 72 is 8

GCF of 65, 72 is 1

GCF of 66, 72 is 6

GCF of 67, 72 is 1

GCF of 68, 72 is 4

GCF of 69, 72 is 3

GCF of 70, 72 is 2

GCF of 71, 72 is 1

There are 24 with the greatest common factor of 1.