When my daughter Bethany came home from school one day, aged around 12, she told me the class had been working on some logic riddles. She launched into an excitable monologue for the next 15 minutes – Bethany always could talk for England so this was an abridged version – so when she paused for breath I told her one of my favourite logic riddles; it goes like this…
“A man lives on the 20th floor of a high-rise tower block. When he goes home from work he gets in the elevator, exits at floor number 12 and walks the remaining eight floors to reach his apartment. Why?”
I told her she could ask me as many questions as she wanted but I could only answer yes or no.
She thought about it for a while and asked some typical questions:
- Was the elevator broken?
- Did the elevator only reach floor number 12?
- Was it part of his exercise plan to walk eight flights of stairs every day?
- Was he visiting somebody on floor number 12?
Of course the answer to all those questions was no and eventually, after a little prompting, she arrived at the solution. For those of you who don’t know the riddle or have not yet worked out the answer, the reason why the man gets out at floor number 12 is because he is a dwarf and he cannot reach beyond button number 12 in the elevator.
Bethany really enjoyed the riddle and asked me if she could pose it to Craig, her older brother, when he arrived home. ‘Of course you can’, I replied. A little while later Craig came in the room and Bethany, full of enthusiasm, said to him ‘Craig, I have a riddle for you’. He got himself a drink and sat down with her so she started.
…… “Right, this dwarf gets in an elevator….. Oh no, wait ……”