What is always in front of you but can’t be seen?

Count The number of F's in the paragraph below:

"FINISHED FILES ARE THE RESULT OF YEARS OF SCIENTIFIC STUDY COMBINED WITH THE EXPERIENCE OF YEARS"

If 21x = 79x, what is the value of x?

Two in a corner, one in a room, zero in a house, but one in a shelter. What am I?

A boy was at a carnival and went to a booth where a man said to the boy, "If I write your exact weight on this piece of paper then you have to give me $50, but if I cannot, I will pay you $50." The boy looked around and saw no scale so he agrees, thinking no matter what the carny writes he'll just say he weighs more or less. In the end the boy ended up paying the man $50. How did the man win the bet?

Eight of us go fourth, not back, to protect our king from an attack. What are we?

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?

I have an apple tree , number of apple in this tree get doubles every week.

On 30th week , the tree gets completely filled with apples :-)



Can you tell me , on what week does my tree is half covered with apples ?

Identify Me

Hint1: I am a god
Hint 2: I am a planet
Hint 3: measurer of heat

A train full of passengers goes through a tunnel. When the train comes out from the other end, there is no single person on the train.

How did it happen?