GCD is greatest common divisor.
The divisors of 100 are,
1, 2, 4,5,10,20,25,50,100
1,2,4,5, work.
We also have the ones where we multiply something with it.
we have the ones with these numbers as factors.
3, 6,7,8 also works.
Essentially all 1-9 works since the gcd is at least 1 and at most 5.
ask if you don't understand anything.
