Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?

What is the fastest way to double your money?

If 24H in a D => 24 hours in a day.
What does "64S on CB" stand for?

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?

There is a circular car race track of 10km. There are two cars, Car A and Car B. And they are at the exact opposite end to each other. At Time T(0), Both cars move toward each other at a constant speed of 100 m/seconds. As we know both cars are at the same speed they will always be the exact opposite to each other.
Note, at the center, there is a bug which starts flying towards Car A at time T(0). When the bug reaches car B, it turns back and starts moving towards the car A. The speed of bug is 1m/second. After 5 hours all three stop moving.
What is the total distance covered by the bug?

Rectify the following equality 101 - 102 = 1 by moving just one digit.

What does the below rebus puzzle mean?

In the image given, you can find several triangles. Can you count them all?

The below given figure comprises of a pattern through which you can determine the missing letter. Can you push your mind to find the pattern and add the missing letter?

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