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.

If it took eight men ten hours to build a wall, how long would it take four men to build it?

Prove that twice of ten is the same as twice of eleven.

I’m orange, I wear a green hat and I sound like a parrot. What am I?

2, 3, 5, 9, 17, _ What is the next number in the sequence?

I have holes on the top and bottom. I have holes on my left and on my right. And I have holes in the middle, yet I still hold water. What am I?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

How is a fly different from a mosquito?

Can you complete the sequence?

192, 021, 222, 324, 252, 627, 2__, 9__?

What can you catch but never throw?