Can anyone tell me a word in the English dictionary which has a silent 'z'?

What number do you get when you multiply all of the numbers on a telephone's number pad?

A train full of passengers goes through a tunnel. When the train comes out from the other end, there is no single person on the train.

How did it happen?

Can you count the number of seconds in a year?

Clue: You need to bother about calculation.

There is something which you can be arrested for attempting but not for successfully completing.

I have lakes with no water, mountains with no stone and cities with no buildings. What am I?

Twenty frogs are sitting on a log floating on the surface of a river. Two of them decide to jump off into the water.

How many frogs are there on the log at this moment?

Count the number of balls in picture below:

A deaf and mute man goes to the train station. Tickets for the train are 50 cents each. The man goes to the ticket booth and hands the man inside just a dollar. The man in the booth hands him two tickets.

How did the man in the booth know to give him two tickets without even looking at him?

A thief is convicted in Mexico. He gets the death penalty. The judge allows him to say the last sentence to determine how the penalty will be carried out. If the thief lies, he will be hanged, if he speaks the truth he will be beheaded. The thief tells the last sentence and to everybody's surprise some minutes later he is set free because the judge cannot determine his penalty. What did the thief say?