What word begins and ends with an E, but has only one letter?

How can you write nineteen in a manner that if we take out one, it becomes twenty?

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?

I have an eye but still cannot see.

Who am I?

I possess a head

I flaunt a tail

But I don't have mouth or legs

Can you find out who I am?

What has one letter and starts with an E?

Seven Robbers robbed a bank and hide the coins in a lonely place.
They decide to divide the money equally the next morning. Two greedy robbers decided to cheat the others and reach the place at night. They equally divided the coins between them, one coin left. So they called another robber and then they decided to divide equally among the three. Sadly again one coin left. The same thing happened to the 4th 5th and the 6th robber.
However, when the 7th robber reached in the morning, they can divide the coins equally.

How many coins were there in total?

If an electric train is travelling south, then which way is the smoke going?

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