What is the coolest letter in the alphabet?

Can you solve this tricky maths equation problem by replacing it? mark with the correct symbol?

19834 -----: 187
15921 -----: 153
17561 -----: 139
13734 -----: ???

You have an empty wine bottle with a cork that has been secured at the top in a normal way. There is a metal ring inside the bottle that is suspended by a string.

How can you make the metal ring drop to the bottom if you are not allowed to touch anything - not the bottle, not the cork, not the thread and not the ring?

Can you replace the question mark with the correct number?

Can you think of a smallest +ve number such that if we shuffle the digits of the number, the new number becomes double the original number?

Find The Missing Number In the Sequence.
6 25 64 ? 32 1

O_er_t_o_

Complete the missing letters of the given word.

Which is heavier: a ton of bricks or a ton of feathers?

I am the fastest animal but cannot climb the tree. What am I?

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?