It's a protector.
It sits on a bridge.
One individual can see directly through it, while others wonder what it hides.

What is it?

In two decks of cards, what is the least amount of cards you must take to be *guaranteed* at least one four-of-a-kind?

There are 2 sand hourglasses.

The small one can measure 5 hours and the large one can measure 7 hours.

How can we measure 16 hours with 2 sand hourglasses running together ?

Imagine a box with two cogwheels, one big with 24 teeth and one small with 8 teeth. The big one is firmly attached to the center of the box which means it does not turn or move while the small one rotates around the big one.

How many times do you think that the smaller wheel will turn compared to the box when it turns once around the big one?

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 ?

What is black when you buy it, red when you use it, and gray when you throw it away?

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

My grandson is about as many days as my son in weeks, and my grandson is as many months as I am in years. My grandson, my son and I together are 120 years. Can you tell me my age in years ?

You are given a cube that is made with the help of 10x10x10 smaller cubes summing up to a total of 1000 smaller cubes. You are asked to take off one layer of the cubes.
How many remain now?