Pro Form: Calculating percentages (decimals)

Hi,

I’m building some kind of ROI calculator, where I need to calculate a percentage value from one of the fields. I use this part of the formula in the calculation field: 1 - ({mtrjcv} / 100). For example, if the field input value equals 80 the calculation should be 1 - (80 / 100) = 0.2. Instead, I’m getting 0.19999999999999996 as a calculation field value.

I’m not good at math, so I used one of the online scientific calculators to check the formula and the result was 0.2. So my question is – Is this a bug or a feature? Thanks.