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

I went to the bookshop and spent one-half of the money that was in my purse.

When I came out, I found that I had as many cents as I had dollars and half as many dollars as I had cents when I went in. Find the money in my purse when I entered the store.

What can run but never walk, have a mouth that never speaks, have a head that never weeps, and have a bed but never sleeps?

If nine thousand, nine hundred nine dollars is written as $9,909,
how should twelve thousand, twelve hundred twelve dollars be written?

Buy me, smell me or deliver me, I do not change.

Who am I?

A pond had 60 fish, out of which, all but 20 died.
How many fishes are now present in that pond?

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?

I drive at an average speed of 30 miles per hour to the railroad station each morning and catch my train. On a particular morning, there was a lot of traffic and at the halfway point, I had averaged only 15 miles per hour. How fast must I drive for the rest of the way to catch my train?

There is a wide field of corn. A goose finds its way into the field and starts running. Can you find out till which point the goose can run into the field?

I am the beginning of the end, and the end of time and space. I am essential to creation, and I surround every place. What am I?