What is the average number of times it would it take to roll a fair 6$6$-sided die and get all numbers on the die? The order in which the numbers appear does not matter.
I had this questions explained to me by a professor (not math professor), but it was not clear in the explanation. We were given the answer $(1-(\frac56)^n)^6 = .5$ or $n = 12.152$
Can someone please explain this to me, possibly with a link to a general topic?