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

If you go to the movies and you're paying, is it cheaper to take one friend to the movies twice, or two friends to the movies at the same time?

Things are just as they seem, right? Well, check again.
Can you count the number of tigers in this picture ?

Find the next number in the series

12, 20, 40, 72, 116, 172 ?

Mr Red Lives in the red house.
Mr Green Lives in the greenhouse.
Mr Yellow Lives in the yellow house.

Who lives in the Whitehouse?

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

Can you find out the next digit in the following series ?

0, 0, 1, 3, 2, 6, 3, 9, 4, 12, 5, ?

A thief enters a store and threatens the clerk, forcing her to open the safe. The clerk says, “The code for the safe is different every day, and if you hurt me you’ll never get the code.” But the thief manages to guess the code on his own. How did he do it?

What goes up but never comes down?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?