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?

Sherlock Holmes was challenged to make a pre-drawn line smaller without erasing it. He did it in fractions of seconds. How?

Why do you find that most of the buildings are deprived of the 13th floor?

Distances from you to certain cities are written below.

BERLIN 200 miles

PARIS 300 miles

ROME 400 milesAMSTERDAM 300 miles

CARDIFF ??? miles

How far should it be to Cardiff ?

What question can you never answer yes to?

Name a key which is hardest to turn.

I possess a head

I flaunt a tail

But I don't have mouth or legs

Can you find out who I am?

Count the number of balls in picture below:

Find three numbers such that

* When we multiply three numbers, we will get the prime numbers.
* The difference between the second and the first number is equal to the third and second.

Can you solve the below geography rebus by decoding the below rebus ?