If eleven plus two equals one, what does nine plus five equal?

A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?

The day after tomorrow will be three days before Tuesday. Can you find out what is today?

Count the squares in the matchstick puzzle below?

Can you replace the X (both small and big x) with the numbers between 1 to 19 such that all the rows of 3 numbers between X (big x) sum to 23?

The chance of Mr John winning the lottery is 10%. All participants lined up and Mr John is 4th in the row. The first three participants lose the lottery.

What is the chance of Mr John now?

Which wheel of car does not rotate when you turn your car right?

Doctor Alex and a bus driver John are both in love with the same woman named Olivia. The bus driver need to go for a long trip of 10 days, Before he left he gave Olivia 10 apples.