If it took eight men ten hours to build a wall, how long would it take four men to build it?

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

If eleven plus two equals one, what does nine plus five equal?

Replace the question mark with the number below given a simple math problem.

The first person saw the bridge step on it and crossed,
the second person saw the bridge did not step on it but crossed,
the third person did not see the bridge did not step on it but crossed.
Who are these people?

Can you make the number 24 by utilizing the numbers 1, 3, 4 and 6? You must use one number only one time and you can use mathematical operation symbols anytime anywhere.

1 dollar = 100 cent
= 10 cent x 10 cent
= 1/10 dollar x 1/10 dollar
= 1/100 dollar
= 1 cent

=> 1 dollar = 1 cent

solve this tricky problem?

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

Make eight squares by moving only two matchsticks.
Note- Square can be of different sizes.

There’s a one-story house in which everything is yellow. Yellow walls, yellow doors, yellow furniture. What colour are the stairs?