What mathematical symbol can be put between 5 and 9, to get a number bigger than 5 and smaller than 9?

The product of three consecutive numbers is 7980.
Then the sum of these consecutive numbers would be?

Here is what you have to do. You have to throw a ball as hard as you can but it must return back to you even if it does not bounce at anything. Also, you have nothing attached to the ball. There is no one on the other end to catch that ball and throw it back at you.

How will you do it?

Can you think of a smallest +ve number such that if we shuffle the digits of the number, the new number becomes double the original number?

Which flower has two lips?

Suppose we lay down two cups in front of you. One of the cups is filled with tea and the other one with coffee. Now we ask you to take a spoonful of tea and mix it with the coffee. At this moment, the coffee cup has a mixture of tea and coffee. You have to take that mixture (spoonful) and add it back to the tea.

Can you now tell if the cup of coffee has more tea or the cup of tea has more coffee?

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.

Which digit occurred maximum times between the number 1 and 1000?

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

Find the next number in the series

12, 20, 40, 72, 116, 172 ?