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.

If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

Suppose that you are trapped on the surface of a frozen lake. The surface is so smooth and ideal that there is no friction at all. You cant make any grip on the ice and no wind is blowing to help you out. You have just a mobile phone with you which has got no reception disabling you to call for help.

How will you plan your escape before you freeze to death on the frozen lake?

There are are five things wrong with this sentence; only geniuses will be able to to spot all of the mitstakes

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

I have branches, but no fruit, trunk or leaves. What am I?

Remove two matchsticks to make the below equation correct.

In an interview, a boy was asked an unusual question 'How two persons sitting with a table in between them can't see each other?' He was unable to reply. Can you?

What is the next number in this series?

4,12,84,3612....

Why is the Hole below a Lock?