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.

On one occasion, A Boy collects 71 rupees in form of 20 paise and 25 paise. He collects a total of 324 coins.

Can you tell me how many 20-paisa and 25-paisa he got?

Can you find out which number multiplied by itself will give the output as 12345678987654321?

Can you identify the direction in which this bus is moving; left or right?

Hint: The bus is moving on the roads of London.

What has many teeth, but cannot bite?

I am a normal creature, but I have five hands. I can even have more but even then I will be considered normal.

Who am I?

Can you calculate the probability of getting a sum of six when a dice is thrown twice?

See the given image carefully. What you have to do is move the blue checkers in the position of the black checkers and vice versa. You are only allowed to move the checker to an adjacent empty space. Do it in the least possible moves.

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 ?

Solve the following series:
AZ, GT, MN, __, YB