Aiyo, when did my Poisson distribution question turn into this
lengthy discussion? o.O
Hmm well, think my example of d/dx (sin x) = cos x is not a good
one. Haha.
But my point is that there are many tedious mathematical
principles which have been simplified for us to use, and we just
take it as it is. The calculator is also used to minimize these
tedious workings to minimum.