How many times do a clock's hands overlap in a day ?

Identify the hidden meaning behind this picture?

Can you arrange four 9's and use at most 2 math symbols, to make the total 100?

Decode the below four famous ciphers:

8P of the SS
1M of the E
1S of the SS
60M in 1H

When monkey rotate the gear, which mark will be hit 1 or 2 ?

A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.

A large water tank has two inlet pipes (a large one and a small one) and one outlet pipe. It takes 3 hours to fill the tank with the large inlet pipe. On the other hand, it takes 6 hours to fill the tank with the small inlet pipe. The outlet pipe allows the full tank to be emptied in 9 hours.

What fraction of the tank (initially empty) will be filled in 0.64 hours if all three pipes are in operation? Give your answer to two decimal places (e.g., 0.25, 0.5, or 0.75).

Eight of us go fourth, not back, to protect our king from an attack. What are we?

Samuel was out for a walk when it started to rain. He did not have an umbrella and he wasn't wearing a hat. His clothes were soaked, yet not a single hair on his head got wet. How could this happen?

In this image, you can see three almost identical Doraemon images. Can you spot the odd one out from them?