Can you convert the number zero(0) into a positive number using just one mathematical operator ?

You are in a room that has three switches and a closed door. The switches control three light bulbs on the other side of the door. Once you open the door, you may never touch the switches again. How can you definitively tell which switch is connected to each of the light bulbs?

Two old friends, Jack and Bill, meet after a long time.

Three kids
Jack: Hey, how are you, man?
Bill: Not bad, got married and I have three kids now.
Jack: That's awesome. How old are they?
Bill: The product of their ages is 72 and the sum of their ages is the same as your birth date.
Jack: Cool..But I still don't know.
Bill: My eldest kid just started taking piano lessons.
Jack: Oh, now I get it.

How old are Bill's kids?

Double it and multiply it by 4. Then divide it by 8 and you’ll have it once more. What number is it?

My location can be determined by the below rebus.
So where am i ?

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

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

What is the longest word in the dictionary?

A train leaves from point A for point B at 80 mph. After half an hour, another train leaves from point B for point A at 60 mph.

Which of the trains will be farther from point A when they meet ?

10+10 and 11+11 can give you the same answer.

Explain how?