The factors of 4 are 1, 2, and 4 because 4 divides by 1, 2, and 4
The factors of 6 are 1, 2, 3 and 6 because 6 divides by 1, 2, 3 and 6
The common factors of 4 and 6 are 1 and 2
The highest common factor of 4 and 6 is 2

 

The factors of 8 are 1, 2, 4, and 8 because 8 divides by 1, 2, 4, and 8
The factors of 24 are 1, 2, 3, 4, 6, 8, 12 and 24 because 24 divides by 1, 2, 3, 4, 6, 8, 12 and 24
The common factors of 8 and 24 are 1, 2, 4 and 8
The highest common factor of 8 and 24 is 8