When Jack was six years old he hammered a nail into his favourite tree to mark his height. Ten years later at age sixteen, Jack returned to see how much higher the nail was. If the tree grew by five centimetres each year, how much higher would the nail be?

We know that the number 7 is the prime followed by a cube. Which next number is also a prime followed by a cube?

Which is heavier: a ton of bricks or a ton of feathers?

What occurs twice in a week, once in a year but never in a day?

What is the next number in this series?

4,12,84,3612....

What can go up a chimney down, but can’t go down a chimney up?

The Little ant seems to be always confused. Do you know why?

Can you convert the number zero(0) into a positive number using just one mathematical operator ?

Find a 9-digit number, which you will gradually round off starting with units, then tenth, hundred etc., until you get to the last numeral, which you do not round off. The rounding alternates (up, down, up ...). After rounding off 8 times, the final number is 500000000. The original number is commensurable by 6 and 7, all the numbers from 1 to 9 are used, and after rounding four times the sum of the not-rounded numerals equals 24.

Count the number of triangles in the below picture?