some people like codes.. they can be fun to solve =P it does take a special kind of mind for it.. but through history; during war times; code breakers saved millions of lives
there are even many good films on it.
The Imitation Game
A Beautiful Mind
im sure there are many others
but may-as-well broaden the scope to other verbal puzzles such as these ones:
1: sisters and brothers i have none.. but this mans father is my fathers son.. who is he in relation to me?
2: I have as many brothers as sisters, but my brothers have twice the number of sisters as brothers. How many of us are there?
3: A princess is as old as the prince will be when the princess is twice as old as the prince was when the princess age was half the sum of their present age.
a: the prince is 20 and the princess is 30
b: the prince is 40 and the princess is 30
c: the prince is 30 and the princess is 40 0
d: the prince is 30 and the princess is 20
e: they are both the same age