What is common among 11, 69, and 88?

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

What does the following represent?

N N N N N N N

A A A A A A A

C C C C C C C

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

Cristina was born in 1888. She just had her 30th birthday today how did that happen?

Irene killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

Manish and Manoj play 5 games of chess.
Both Manish and Manoj win the exact same number of games. There is no tie at all.

How?

Take away the whole and some still remain. What is it?

A man stands on one side of a river, his dog on the other. The man calls his dog, who immediately crosses the river without getting wet and without using a bridge or a boat. How did the dog do it?

A boy purchased a book from a bookkeeper and gave him $100.
The cost of the book is $50 but the bookkeeper has no change, so he gets the change from the next shop and returns the boy his $50.

After some time the next shopkeeper came with the $100 note and told the bookkeeper that the note was a fraud, so he took the money back.

How much loss did the bookkeeper face?