I never stop running even when I standstill. If I am formed by joining two identical bodies together, can you guess who I am?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

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

By using 'because' continuously three times, can you make an English statement ?

A girl is twice as old as her brother and half as old as her father. In 50 years, her brother will be half as old as his father. How old is the daughter now?

A man is trapped in a room. The room has only two possible exits doors. Through the first door there is a room constructed from magnifying glass. The blazing hot sun instantly fries anything or anyone that enters. Through the second door there is a fire-breathing dragon. How does the man escape?

Replace all '*' with digits 1, 2, 3, 4, 5 and 6 to make below statement true.

* *
x *
=====
* * *

If you say my name, I will no longer exist. What am I?

In order to complete the racing competition, the Mexico racetrack has to submit its top and the most famous three horses to win the competition. Due to an electrical storm, all the records are cleared and no one knows which horse holds the record. They all look identical and it becomes even more difficult to differentiate the horses. There are 25 horses in the Mexico racetrack. But there can be only five horses at a time on the track. What will the least number of races that can be conducted to find out the three fastest horses?

10+10 and 11+11 can give you the same answer.

Explain how?