Can you find out the number that should replace the question mark with a valid reason?

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

I have four wings but can't fly.
I express no emotions.
I am found on the exact spot every time you look.
I keep toiling away with a little sound.

Do you know what am I?

I live in a bowl. I can swim. I have a tail. I also have fins and big eyes. What am I?

If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

Twice ten are six of us,

Six are but three of us,

Nine are but four of us;

What can we possibly be?

Would you know more of us?

Twelve are but six of us,

Five are but four, do you see?

What are we?

There are five vowels (a, e, i, o, u) in the English language.
Can you tell us a word that contains all these vowels?

During which month do people sleep the least?

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

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?