A man lives on the 14th floor.
Every day he gets in the lift, presses the ground floor button, descends and gets out.
In the evening, he returns, gets in the lift and presses the 10th floor button.
He gets out of the lift on the 10th floor and walks up the stairs to his apartment.
(Courtesy of Edward de Bono)
1.2. A man lives on the twelfth floor of an apartment building. Every
morning he takes the elevator down to the lobby and leaves the building. In
the evening, he gets into the elevator, and, if there is someone else in the
elevator -- or if it was raining that day -- he goes back to his floor
directly. However, if there is nobody else in the elevator and it hasn't
rained, he goes to the tenth floor and walks up two flights of stairs to his
room. (MH, from _How Come?_)
1.2 answer: The man is a midget. He can't reach the upper elevator
buttons, but he can ask people to push them for him. He can also push them
with his umbrella. I've usually heard this stated with more details: "Every
morning he wakes up, gets dressed, eats, goes to the elevator..." In the
other direction, for a shorter problem statement, leave out the "someone
else in the elevator" and "if it was raining" parts, and just say on his
return to the building he always goes to the tenth floor. Ron Carter
suggests a nice red herring: the man lives on the 13th floor of the
1.2a. Variant: Emily regularly visits the twelfth floor of an apartment
building by going to the tenth floor and walking up two flights of stairs.
Last year she only took the elevator to the ninth floor. (_Math for Girls_)
1.2a answer: Emily is a child; she can only reach the tenth-floor button,
and last year she could only reach the ninth-floor button.