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?

What three numbers, none of which is zero, give the same result whether they’re added or multiplied?

Why do you find that most of the buildings are deprived of the 13th floor?

Pronounced as one letter,
And written with three,
Two letters there are,
And two only in me.
I am double, I am single,
I am black blue and grey,
I am read from both ends,
And the same either way.

I always drive my customer away.

Who am I?

John has played 50 ODI's and his average is 50. How many runs should he score in his 51st ODI, so that his average score jumps to 51?

If there are fifteen crows on a fence and the farmer shoots a third of them, how many crows are left?

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?

John bought 150 chocolates but he misplaced some of them. His Father asked him how many chocolates were misplaced.
He gave the following answer to him:
If you count in pairs, one remains
If you count in threes, two remain
If you count in fours, three remain
If you count in fives, four remain
If you count in sixes, five remain
If you count in sevens, no chocolate remains.

Can you analyze the statements and tell us how many chocolates were lost?

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