A soccer team just became first in the national league. The players which were on the field just after the referee blew the final signal wanted to congratulate each other by shaking hands. Assuming that each player shook hands with every other player only once, how many time were the hands shaken in total? (There are of course 11 players in a soccer team)

If you would fold a letter in two fifty times, how thick should the enveloppe be that can fit the letter? Assume that the thickness of a piece of paper is about 0.05 mm.

Two times two is equal to two and two. But are there more number pairs for which the sum of the numbers is is equal to the product of the numbers? The numbers may be different.