Question

What is the most important part of the decimal system

Answer 1

The decimal... lol  thats what mt grandmom told me

Answer 2

The decimal point without the decimal point there is no decimal at all. 
i hoped that works ill give you an example if you are still confused 

if you are trying to turn this number 89 into a decimal you would have to do 8.9 if you don't than  89 is just a number not a decimal if you forget the decimal you will more than likely get the question incorrect.