How can a man go eight days without sleep?

What is both possible and impossible at the same time?

A train full of passengers goes through a tunnel. When the train comes out from the other end, there is no single person on the train.

How did it happen?

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

I know a nine-letter word having only one vowel.
Do you ?

I have branches, but no fruit, trunk or leaves. What am I?

Find the next number in the sequence

1, 2, 6, 21, 88, __?

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

Using four sevens (7) and a one (1) create the number 100. Except for the five numerals, you can use the usual mathematical operations (+, -, x, :), root and brackets ()

Find the last number in the series below:

voN luJ yaM raM ---