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.

Can you find a number that lies one third of the distance between 1/3 and 2/3?

'S' refers to the number of seconds in a day and 'H' refers to the number of hours in ten years. Which quantity out of these two is greater?

Can you think of any three-dimensional shape that comprises of exactly two surfaces?

In case you were starting to feel confident, this one was meant for third graders in Vietnam. The answer is 66, but we don't blame you for scratching your head about how they got there.

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

Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

How many people must be gathered together in a room, before you can be certain that there is a greater than 50/50 chance that at least two of them have the same birthday?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

How many triangles are there on the puzzle below?