During which month do people sleep the least?

I am white when I am dirty, and black when I am clean. What am I?

As easy as you can get into me, it is as hard to get out of me.

Do you know what I am?

What word is represented by this rebus?

What are the 50th, 63rd and 100th numbers in the sequence below?
4, 5, 8, 8, 9, 9, 12, 13, 13, 13, 17, 18, ...

Rearrange the letters in "new door" to make one word.

Find the next number in the series.
1 10 24 43 67 ?

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

Two natural numbers have a sum of less than 100 and are greater than one.

John knows the product of the numbers and Jacob knows the sum of numbers.

The following conversation takes place between them:
John: 'I am not aware of those numbers.'
Jacob: 'I knew you wouldn't be. I am not aware myself.'
John: 'Now I know them!'
Jacob: 'Now I know them, too!'

What are the two numbers?

What is the fastest way to double your money?