I have teeth but i don't bite. Who Am I ?

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?

An ape is trying to climb on a pole that is 60 feet high. Due to the slippery surface, the ape climbs 3 feet in a minute only to slip back 2 feet.

How much time do you think the monkey will take to reach the top of the pole?

Distances from you to certain cities are written below.

BERLIN 200 miles

PARIS 300 miles

ROME 400 milesAMSTERDAM 300 miles

CARDIFF ??? miles

How far should it be to Cardiff ?

I am the one who remains awake when you sleep. But I need to rest when you awake. Who Am I?

How many times do a clock's hands overlap in a day ?

There is one thing that goes round the house and also inside the house but never even share a brief touch. What is it?

Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.

The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

What does this mean?

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