Count the number of triangles in the below picture?

Assume there are approximately 5,000,000,000 (5 billion) people on Earth. What would you estimate to be the result, if you multiply together the number of fingers on every person's left hand? (For the purposes of this exercise, thumbs count as fingers, for five fingers per hand.) If you cannot estimate the number then try to guess how long the number would be.

A number can be multiplied by multiple of nine
i.e 9 18 27 36 45 ...

and the resulting number consist of only one digit.

Can you identify the number ?

There is a square of a particular number which when doubled, becomes 7 more than its quarter.

Can you find the number?

That attorney is my brother, testified the accountant.

But the attorney testified he didn't have a brother.

Who is lying?

10 people came into a hotel with 9 rooms and each guest wanted his own room. The bellboy solved this problem.
He asked the tenth guest to wait for a little with the first guest in room number 1. So in the first room, there were two people. The bellboy took the third guest to room number 2, the fourth to number 3, ..., and the ninth guest to room number 8. Then he returned to room number 1 and took the tenth guest to room number 9, still vacant.
How can everybody have his own room?

Replace the question mark with the number below given a simple math problem.

I have cities, but no houses. I have mountains, but no trees. I have water, but no fish. What am I?

You can hear me, but you can't touch or see me.

What am I?

What is Luis Suarez's (Soccer Player) favorite tea?