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
building.

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.