An American nightclub called 'The Coconut Grove' had a terrible fire in which over 400 people died. A simple design flaw in the building led to a high death toll. Subsequently, regulations were changed to ensure that all public buildings throughout the country eliminated this one detail, which proved deadly. What was it?

Which wheel of car does not rotate when you turn your car right?

Double it and multiply it by 4. Then divide it by 8 and you’ll have it once more. What number is it?

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

John is found dead in his office at his desk. The police have narrowed the suspects down to three people: Mrs. Jacob, John’s wife Hena and his business partner Jason . All three visited John on the day of his murder, but all three provide the police with stories of explanation as to the reason for their visit.
Police found John with his wrist watch still on his right arm, a torn up picture of his wife laying on the floor beside the trash can, and an ink pen in his right hand. On the desk, the police found a name plate, a telephone that was off the hook, and a personal calendar turned to the July 5th page with 7B91011 written on it. After examining this evidence, the police knew their suspect. Who was it ?

Who is that with a neck and no head, two arms and no hands? What is it?

What mathematical symbol can be put between 5 and 9, to get a number bigger than 5 and smaller than 9?

The more of this there is, the less you see. What is it?

If I put in one canary per cage, I have one bird too many. If I put in two canaries per cage, I have one cage too many. How many cages and canaries do I have?

What can run but never walk, have a mouth that never speaks, have a head that never weeps, and have a bed but never sleeps?