There are an infinite number of them.
If you're only interested in positive, whole numbers, then there are 8 of them:
1, 2, 4, 5, 8, 10, 20, and 40.
Eleven.
The gcf is 8
2..
40/8=5
40 times.
Only the number 1.
It is 280
easy, 40
Their HCF is 8
40
40 of them.
u go say it is 40 u put 40 over 100 and ur answer is 40% :)