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

In Greek mythology, the Sphinx sat outside of Thebes and asked this riddle of all travellers who passed by. If the traveller failed to solve the riddle, then the Sphinx killed him/her. And if the traveller answered the riddle correctly, then the Sphinx would destroy herself. The riddle:

What goes on four legs in the morning, on two legs at noon, and on three legs in the evening?

Oedipus solved the riddle, and the Sphinx destroyed herself.

It has horns but can’t beep. It is like to bleat but It is not a sheep. What is it?

Can you name four days which start with the letter 'T'?

A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?

I have a head like a cat and feet like a cat, but I am not a cat. What am I?

Two girls were born to the same mother, on the same day, at the same time, in the same month and year and yet they're not twins. How can this be ?

A Japanese ship was en route to a mission on foreign seas. The captain of the ship felt tired and thought of taking a bath. He went for taking the shower and removed his diamond ring and Rolex and kept them on the table. When he returned after taking the bath, he found that the ring and watch were stolen.

He called the five members of the crew whom he suspected and asked them what they were doing for the last 15 minutes.

The Italian cook (with a butcher knife in hand): I was in the fridge room getting meat for cooking.

The British Engineer (with a high beam torch in hand): I was working on a generator engine.

The Pakistani seaman: I was on the mast correcting the flag which was upside down by mistake.

The Indian Radio officer: I was trying to make a contact with the company to inform them about our position.

The American navigation officer: I am on night watch, so I was sleeping in my cabin.

Upon listening to them, the captain caught the lying member. Who do you think stole the valuables?

I’m tall when I’m young, and I’m short when I’m old. What am I?

If we change the South-East direction into North and North-East into West and all others similarly.
Can you find out which direction will be in the place of South-West direction?