Name a key which is hardest to turn.

Assume there are approximately 5,000,000,000 (5 billion) people on Earth. What would you estimate to be the result, if you multiply together the number of fingers on every person's left hand? (For the purposes of this exercise, thumbs count as fingers, for five fingers per hand.) If you cannot estimate the number then try to guess how long the number would be.

The measurement of time, That can't be found on a clock, But can be looked upon on a map.

Who is He ?

A patient was diagnosed with some ailment. He was given five different tablets to take at night at an interval of 15 minutes.

How long will it take the patient to consume all the five tablets?

A boy and a girl are sitting on the porch.
"I'm a boy," says the child with black hair.
"I'm a girl," says the child with red hair.
If at least one of them is lying, who is which?

I am a five-letter word and comprises two different vowels and three same consonants. I am so strong that I can spoil your entire work.

Can you find out who am I?

1 + 9 + 8 = ?
considering, 28 + 8 + 92 = 10

John was driving a bus and got stuck when passing through an underpass. Then came Jacob with a needle and got the bus out of the underpass.

What did the boy do?

At a bar, three friends, Mr Green, Mr Red and Mr Blue, were having a drink. One man was wearing a red suit; one a green suit; and the other a blue suit. 'Have you noticed,' said the man in the blue suit, 'that although our suits have colours corresponding to our names, not one of us is wearing a suit that matches our own names?' Mr Red looked at the other two and said, 'You're absolutely correct. What colour suit is each man wearing?

Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.