How can one talk without saying a single word?

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?

We know that the number 7 is the prime followed by a cube. Which next number is also a prime followed by a cube?

Using four sevens (7) and a one (1) create the number 100. Except for the five numerals, you can use the usual mathematical operations (+, -, x, :), root and brackets ()

Two in a corner, one in a room, zero in a house, but one in a shelter. What is it?

A 3 digit number is such that it's unit digit is equal to the product of the other two digits which are prime. Also, the difference between it's reverse and itself is 396.

What is the sum of the three digits?

If an electric train is travelling south, then which way is the smoke going?

At a party, there are five people and a whole round cake lying at the centre of the table. Only four people will make a cut and take their piece and the last one will get the remaining piece on the table. How can they make sure that everyone gets a 1/5th of the piece?

What have one eye but still cannot see?

What can you hold in your right hand, but never in your left hand?