What 4-letter word can be written forward, backward or upside down, and can still be read from left to right?

I am a word of 12 alphabets.

* Alphabets 12, 4, 7, 2, 5 : Eastern beast of burden
* Alphabets 1, 8, 10, 9 are street made famous by Sinclair Lewis.
* Alphabets 11, 3, 6 are past.

On whole it means a person suffering from delusions of greatness.

What Is it ?

What is the below Rebus indicate?

A bridge is about to collapse. There are four people P, Q, R and S on one of the sides. Before the bridge collapses, they want to cross it. Now since the bridge is too weak, it can only stand the weight of two people at a time. Also, it is night time and nothing is visible. They have just one torch with them.

Now P takes one minute to cross the bridge, Q takes two minutes to cross, R takes five minutes to cross and S takes ten minutes to cross.

The bridge will collapse in seventeen minutes. How will they be able to cross the bridge before it collapses?

What building has the most stories?

What has no start, end, or centre?

What has many keys but can’t open a single lock?

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

A finger goes in me. You fiddle with me when you're bored. The best man always has me first. What am I?

Prove that twice of ten is the same as twice of eleven.