What number can't divide 4 and400 but can divide 100?
50, 20, 25, 10, 5, and 12.5 don't divide into 4 but all of them
divide into 400. There is no number that I can think of that is not
a factor of 400 but is a factor of 100 as 100 is a factor of 400,
so whatever number makes up 100 must make up 400.