What number should come in place of the question mark below?

When my father was 31 I was 8. Now he is twice as old as me. How old am I?

Can you spot the hidden girl in the picture below?

Can you convert the number zero(0) into a positive number using just one mathematical operator ?

Can you name four days which start with the letter 'T'?

A girl says this to her best friend: “I was born in 1955, and I celebrated my 17th birthday last weekend.” Her best friend thinks she’s lying, but she’s actually correct. How is that possible?

13 decks of cards have been mixed. What is the minimum number of cards that must be taken out from the above-mixed cards to guarantee at least one 'four of a kind?

Which part of London exists in France as well ?

Which fur should we be getting from the Lion?

I organized a small get together at my home.
In the party , i have a barrel with some whiskey in it.

Suddenly Guest 1 say 'I bet this barrel of whiskey is more than half full'.
'No, it's less than half full' Guest 2 replied.

I don't have any measuring instrument and without removing whiskey from it , how can i determine which of the guest is right ?