Can it be possible to build a house that has all its four walls facing towards the South?

Can you tell a 3D object that has just two surfaces?

13 decks of cards have been mixed. What is the minimum number of cards that must be taken out from the above-mixed cards to guarantee at least one 'four of a kind?

Can you find the ages of a son, father and grandfather based on the following facts?
The sum of the ages of grandfather, father and son is 140 years.
The age of the son in months is the same as the grandfather in years.
The age of the son in days is the same as the father in weeks.

How do you go from 98 to 720 using just one letter?

You are trapped in a room with two doors. One leads to certain death and the other leads to freedom. You don't know which is which.
There are two robots guarding the doors. They will let you choose one door but upon doing so you must go through it.
You can, however, ask one robot one question. The problem is one robot always tells the truth, the other always lies and you don't know which is which.
What is the question you ask?

There's one "sport" in which neither the spectators nor the participants know the score or the leader until the contest ends.

What is it?

Solve the counting riddle by identifying the number of triangles in the given picture.

How is a fly different from a mosquito?

2 ladies and 2 girls need to cross a river in a boat big enough for 1 LADY or 2 girls. How do they do it?