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

An explorer goes on an exposition in the jungle. He sets up camp in the middle of the jungle. The next morning he sees something with a head and a tail, but he is not afraid. What did he see in his bag?

There is a square piece of paper with a hole that is denoted by the circle on the top right side in the given picture. You have to cut the paper in a manner that it forms two and only two separate pieces of paper and then rearrange the pieces in a manner that the holes come in the centre of the paper.

John named his first son Alpha, second Beta, third Charlie and fourth Delta. What is the fifth son's name?

A guard is positioned at the one side of the bridge saying ‘A’. His task is to shoot all those who try to leave from ‘A’ to the other side and say ‘B’. He also need to welcome the person who comes from another side ‘B’ to his side ‘A’. The guard comes out of his post every 1 hour and looks down the bridge for any people trying to leave. You are at side ‘A’ and wish to go to another side ‘B’. you also know that it would take 1:45 hr to cross the bridge. How will you cross the bridge?

Before Balboa discovered the Pacific Ocean, which was the largest ocean before that?

1 + 9 + 8 = ?
considering, 28 + 8 + 92 = 10

Find the 8 in the below-given Image.

Assume there are approximately 5,000,000,000 (5 billion) people on Earth. What would you estimate to be the result, if you multiply together the number of fingers on every person's left hand? (For the purposes of this exercise, thumbs count as fingers, for five fingers per hand.) If you cannot estimate the number then try to guess how long the number would be.