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

There was an aeroplane crash, every single person died, but two people survived. How is this possible?

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?

You are trapped in a room with two doors. One leads to certain death and the other leads to freedom. You don't know which is which.
There are two robots guarding the doors. They will let you choose one door but upon doing so you must go through it.
You can, however, ask one robot one question. The problem is one robot always tells the truth, the other always lies and you don't know which is which.
What is the question you ask?

What is the longest word in the dictionary?

What is common among 11, 69, and 88?

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.

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?

Take 9 from 6, 10 from 9, 50 from 40, and leave 6.

How Come ??

In the Mexico City area, there are two Houses H1 and H2. Both H1 and H2 have two children each.
In House H1, The boy plays for Mexico Youth academy and the other child plays baseball.
In House H2, The boy Plays soccer for his school in Mexico and they recently have a newborn.

Can you prove that the probability of House-H1 having a girl child is more than that of House-H2?