A number can be multiplied by multiple of nine
i.e 9 18 27 36 45 ...

and the resulting number consist of only one digit.

Can you identify the number ?

How many pluses should we put between the digits of 987654321 to get a total of 99, and where?

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.

Which three-digit number, made of consecutive digits, like 567, is 2 less than a cube and 2 more than a square?

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

John can eat 27 chocolates in an hour, Jacob can eat 2 chocolates in 10 minutes, and Jolly can eat 7 chocolates in 20 minutes. How long will it take them to share and eat a box of 120 chocolates whilst playing Chess?

Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

Can you find out the remainder when 3^300 is divided by 5?

Can you find out the smallest number that can be conveyed as the sum of three squares in three unique ways?

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.