What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

Count the number of triangles in the given picture.

What is common among 11, 69, and 88?

Cristina leaves home and then she makes exactly 3 left turns and returns home where she found 2 girls wearing the mask.

Who are these two masked girls?

Why Aeroplane windows are round?

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?

If an earthquake is 1 point higher on the Richter Scale than another earthquake which is actually 10 times stronger, how much stronger would an earthquake be if it was just half a point higher on the Richter scale?

What has many teeth, but cannot bite?

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.

You’ll find me on Mercury, Earth, Mars, Jupiter, Saturn, and Uranus. But never Neptune, or Venus. What am I?