It's sometimes, because let's say I have 4/5 right? So when in a percent it's 80%. I suppose you could turn it into a a decimal of 80/100 but no not always. 3295729357/1000000000000. That doesn't have a denominator of 100, so yeah.
I'm not sure what your asking but what I can gather from the question is when turning a percent into a fraction yes, you woud always put the denominator as 100
