In most statistical models to represent easy percentages, circle is mostly preferred. It is purposefully designed or rather allotted for functions that included 100%. A pie chart in technical terms. Imagine an uneaten cake would represent a 100%. In most case scenarios, when you eat one slice of the cake. You take a portion that decreases it 100% or a whole presentation, for instance you took 25% slice of cake, what’s left will be 75% and then when you put back again, the 25% slice will present the whole 100%. In words, 25% slice of a cake you take, what’s left will just a portion 75% and unless you put it back it will be whole again.