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.

It's pretty hard to give up.
If you remove a part of it, you will be left with a bit.
Even if you remove another part, the bit still remains.
Remove one more and it still remains.

What is it?

You knock a Table over in the library, and suddenly 20 eyes are looking at you.

How many triangles can you count in the figure given?

Most people think of me as money. But when they find me in the water, they won’t get any money out of me. What am I?

What jumps when it walks and sits when it stands?

What's the only room from which no one can enter or leave

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

I taste better than I can smell. Who am I?

On the dull night when the blonde was dozing, she heard an odd clamour and she saw that there was a bizarre man with a gun simply outside her home. So she raced to the telephone to call the police, however, she can't dial 911. Why?