These puzzles have a combinatorial or probabilistic basis. They involve finding the number of ways something can be done, or how likely something is to happen. Basically, you just need to be able to count things carefully.
How many distinct ways are there to colour the six faces of a cube using six different colours, and applying a different colour to each face. Cubes which could be rotated to look the same as each other are not counted as distinct.

I have two identical packs of cards. I take each pack and shuffle it separately, placing them both face down in the table. I then procede to play a game of snap with myself - being a mathematician I have no friends. I compare the top card from each pile, and then compare the second card from each pile, ... and so on. What is the probability that I continue in this way all the way down the piles, and never find an exact match in the 52 pairs of cards?
Given 23 randomly selected people, what is the probablilty that at least two of them have their birthday on the same day of the year?
[ You may assume that none of them was born on 29th February, and that any other day of the year is equally likely to ocur as a birthday. ]