Question

Highest common factor of 24 and 40

Answer 1

24 = 2*12= 2*4*3= 2*2*2*3
40 = 5*8 = 5*2*2*2

Greatest common factor is what the number have in common as factors.
We see that both numbers have (2*2*2) = 8
So, greatest common factor is 8.

Answer 2

8 is the highest common factor