A man in a car saw a Golden Door, Silver Door and a Bronze Door. What door did he open first?

Can you find a seven digit number which describes itself. The first digit is the number of zeros in the number. The second digit is the number of ones in the number, etc. For example, in the number 21200, there are 2 zeros, 1 one, 2 twos, 0 threes and 0 fours.

What time is it when an elephant sits on a fence?

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

Below the four parts have been reorganised. The four partitions are exactly the same in both arrangements. Why is there a hole?

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?

A new clothing store has a unique method of pricing items. A vest costs $20, a tie costs $15, a blouse costs $30, and underwear costs $45. How much would pants cost?

Below, you will find the mathematical proof that 10 equals 9.99999?. But is that possible or there is something wrong about it? Can you find the error?

x = 9.999999...
10x = 99.999999...
10x - x = 90
9x = 90
x = 10

What is the last thing you take off before bed?

I can be cracked, made, told, and played. What am I?