What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

Why is Saturday stronger than Monday?

Can you find the largest Three-digit number whose sum is 14 and whose square is less than 5,00,000?

A man hijacks an aeroplane transporting both passengers(8 of them) and valuable cargo. After taking the cargo, the man demands nine parachutes, puts one of them on, and jumps, leaving the other eight behind. Why did he want eight?

See the given image carefully. What you have to do is move the blue checkers in the position of the black checkers and vice versa. You are only allowed to move the checker to an adjacent empty space. Do it in the least possible moves.

Jessica is telling her friends this story and asks them to guess if it’s the truth or a lie: “There was a man sitting in a house at night that had no lights on at all. There was no lamp, no candle, and no other source of light. Yet, he sat in the house and read his book happily.” Her friends say she’s lying, but Jessica corrects them and says she’s telling the truth. Jessica’s story is true—but how?

Find out the number of circles in the given picture having Illusion

What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps?

A train full of passengers goes through a tunnel. When the train comes out from the other end, there is no single person on the train.

How did it happen?