The person who makes it has no need for it; the person who buys it has no use for it. The person who uses it can neither see nor feel it. What is it?

Next Number in the Series,

5, 16, 49, 104, ?

A plane crashed between the border of Mexico and America. Where do you bury the survivors?

Count the number of triangles in the below picture?

How can you make the following equation true by drawing only one straight line: 5+5+5=550 ?

If we add four times the age of John four years from now to five times his age five years from now we get ten times his current age.

How old will John be two years from now?

Can you count the number of triangles inside a triangle?

A large water tank has two inlet pipes (a large one and a small one) and one outlet pipe. It takes 3 hours to fill the tank with the large inlet pipe. On the other hand, it takes 6 hours to fill the tank with the small inlet pipe. The outlet pipe allows the full tank to be emptied in 9 hours.

What fraction of the tank (initially empty) will be filled in 0.64 hours if all three pipes are in operation? Give your answer to two decimal places (e.g., 0.25, 0.5, or 0.75).

People make me, save me, change me, raise me. What am I?

When it is alive we sing, when it is dead we clap our hands. What is it?