When you are teaching people something, you have to explain it to the fullest so that it will be clear to the audience and not vague, so you don't keep the audience hanging and confused, thereby making your audience to induce their own meaning into what you are saying. When you said "calculation" what sort of calculations are you talking about? There are different types of calculations and I don't know the one you are referring to in this context. Are talking about financial calculation, time calculation, elementary calculation etc. So which of the calculation are you referring to?