12 Oct
2013
12 Oct
'13
8:15 p.m.
Q. What do you get when you differentiate sin x with respect to x a hundred times? A. You get cos x every time. :-) Jim Propp P.S. The chain of musings that led me to this riddle started with the literal inaccuracy of the way English speakers describe m times n as what you get when you "add m to itself n times". This is wrong in two ways: we actually add n-1 times, not n times, and what we add m to is not "itself" (except the first time) but rather the running total of all the m's previously added.