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.

Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?

Spot the cat in the picture below

An evil man kidnapped someone and made them take one of two pills. One was harmless, but the other was poisonous. Whichever pill the victim took, the kidnapper took the other one. The victim took their pill with water and died. The kidnapper survived. How did the kidnapper get the harmless pill?

What Does this text mean:

important=important

Replace all '*' with digits 1, 2, 3, 4, 5 and 6 to make below statement true.

* *
x *
=====
* * *

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?

What can go through glass without breaking it?

What does this simple rebus mean?

What does the following represent?

N N N N N N N

A A A A A A A

C C C C C C C