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.

Double it and multiply it by 4. Then divide it by 8 and you’ll have it once more. What number is it?

What's a single-digit number with no value?

You need to arrange three 7 and mathematical symbols to form number 1?

On one occasion, A Boy collects 71 rupees in form of 20 paise and 25 paise. He collects a total of 324 coins.

Can you tell me how many 20-paisa and 25-paisa he got?

John drives to his office at 20km/hr. After reaching the office, he realizes that today is a holiday. He went back at an average speed of 30km/hr. Discounting the time spent in the stoppage what was the average speed of his journey?

I am an odd number. Take away a letter and I become even. What number am I?

There is one four-digit whole number n, such that the last four digits of n2 are the original number n

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

The square root of number 121 is "11". What is the square root of the number "12345678987654321."?