100 prisoners are stuck in the prison in solitary cells. The warden of the prison got bored one day and offered them a challenge. He will put one prisoner per day, selected at random (a prisoner can be selected more than once), into a special room with a light bulb and a switch which controls the bulb. No other prisoners can see or control the light bulb. The prisoner in the special room can either turn on the bulb, turn off the bulb or do nothing. On any day, the prisoners can stop this process and say "Every prisoner has been in the special room at least once". If that happens to be true, all the prisoners will be set free. If it is false, then all the prisoners will be executed. The prisoners are given some time to discuss and figure out a solution. How do they ensure they all go free?

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

What's the only room from which no one can enter or leave

We know that the number 7 is the prime followed by a cube. Which next number is also a prime followed by a cube?

What Time Should the last watch show in the below figure?

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

How many cubic feet of dirt are in a hole of one foot deep, three feet long, and two feet wide?

He loves to dance, twist and prance, he shakes his tail, and as a way he sails, wingless he flies into the sky. What is he?

What question can you never answer yes to?

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?