If you say my name, I will no longer exist. What am I?

Fate has decided that you will only be pleased to meet me when you need me

Maybe that is why, when I am working, I start working

However annoying I may be to the regulars, the little ones are always inspired

I will always be waiting if you try to reach me

How many of you can guess my name, let me see

Why 1729 is a magic number? Answer Logically.

What jumps when it walks and sits when it stands?

What demands an answer, but asks no questions

I look flat, but I am deep. Hidden realms I shelter. Lives I take, but the food I offer. At times I am beautiful. I can be calm, angry, and turbulent. I have no heart but offer pleasure as well as death. No man can own me, yet I encompass what all men must have. What am I?

If,

A = 1

B = 2

C = 3

...

...

Z = 26.

Based on above rule, you need to find an eleven letter word whose letter sum is equal to 52.

I am the fastest animal but cannot climb the tree. What am I?

What is the riddle which can be asked all day with a different correct answer each time.

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