You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

If,

A + B = C
D - C = A
E - B = C

Based on the above equations, find out the answer for:

D + F = ?

Once while in his court, King Akbar asked Birbal to write something on a wall that makes one sad when read in good times and makes one happy when read in sad times.

He took only a few moment and wrote something that fit the requirements. What did he write?

Consider this: Arnold Schwarzenegger has a big one. Michael J. Fox has a small one. Prince doesn’t have one. The Pope has one but never uses it. Bill Clinton has one and uses it all the time. What is it?

What is the riddle which can be asked all day with a different correct answer each time.

How can you take 2 from 5 and leave 4?

A shepherd had 18 sheep, out of which, all but ten died.

Can you tell us how many sheep was he left with?

"That Restaurant always remains crowded. This is the reason why nobody goes there".

Can you find a flaw in this statement?

Before Mount Everest was discovered, what was the highest mountain in the world?

Only one color, but not one size,
Stuck at the bottom, yet easily flies.
Present in sun, but not in rain,
Doing no harm, and feeling no pain.
What is it?