I am an odd number. Take away a letter and I become even. What number am I?

I never was there, I am always to be.
You have never ever seen me, not ever you will.
Yet I am the confidence of everyone.

Who Am I?

If I put in one canary per cage, I have one bird too many. If I put in two canaries per cage, I have one cage too many. How many cages and canaries do I have?

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

There are are five things wrong with this sentence; only geniuses will be able to to spot all of the mitstakes

A donkey is behind another donkey
I'm behind that second donkey
But there is a whole nation behind me

It is a murder you can describe in a word.

You along with your friend are standing in front of two houses. Each of those houses inhabits a family with two children.

Your friend tells you the below two facts:
1) On your left is a family that has a boy who likes accounts but the other child loves science.
2) On the right is a family with a seven-year-old boy and a newborn baby.

You ask him, "Does either of the family have a girl?"

To this, he replies, "I am not quite sure. But can you guess that? If you are right, I will give you $500."

Which family do you think is likely to have a girl?

The more of this there is, the less you see. What is it?

Why do we preferably have round manhole covers and not square ones?

The more you take me, the more you leave me behind.
Who Am I?