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.

What is the centre of gravity?

What is the largest amount of money that you can possess in change and still if someone asks you for a dollar, you won't be able to give?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

Teacher ask the student

'Why are you standing on that chair in music class ?'.

what did student replied ?

He runs but never walks. Murmurs, but never talks. Has a bed, but never sleeps. And has a mouth, but never eats?

John was working on a Chemical Mixture whose weight comprise 90% liquid and 10% solid. The total weight of the mixture is 20 pounds. After a while, John noticed that some of the liquid evaporated and now the liquid comprises just 50% of the weight.

What is the weight of the chemical mixture now?

At my favorite fruit stand,
an orange costs 18,
a pineapple costs 27,
and a grape costs 15.
Using the same logic, can you tell how much a mango costs?

What does a man do only once in his lifetime, but women do once a year after they are 29?

What demands an answer, but asks no questions