To find the greatest common factor, we take these numbers and analyze them into prime numbers
Example : 48 = 2^4 x 3
112 = 2^4 x 7
80 = 2^4 x 5
Now, the greatest common factor of them all will be the prime number (with power) that they all have in common.
So, they all have 2^4 -> Their greatest common factor is 2^4
Side note : Example with 10 and 80, we analyzed to 2 x 5 and 2^4 x 5, here their common prime numbers are actually 2 and 5 -> 2 x 5 = 10
(So, if there is a prime number and a prime number that is powered, we take the original one)
