Why is 6 afraid of 7?

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

Assume there are approximately 5,000,000,000 (5 billion) people on Earth. What would you estimate to be the result, if you multiply together the number of fingers on every person's left hand? (For the purposes of this exercise, thumbs count as fingers, for five fingers per hand.) If you cannot estimate the number then try to guess how long the number would be.

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

Railroad Crossing, look out for the cars. Can you spell that, without any R's ?

This is a classy optical illusion puzzle. What more you can find except bricks in the image below?

Can you name three consecutive days without using the words Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, or Sunday?

John enters a small room. The Door Closes.
When the door opens, John is in a larger room.

Explain?

Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?

What does below Rebus mean ?

esgg sgeg gegs gsge