I am a prime number.
The double of myself is equal to the square of me.

which number am I?

In The 1st month of this year(the year 2013), I noticed that the date 13-1-13 (13 January 2013) is special.

This date is special as:

Date * Month = Year.

Can you figure out which year of this century has a maximum number of such dates?

John was running from 40 thieves. John has got 3 gold boxes which weigh as 4kg, 2kg, and 1kg respectively. A witty man asked John to stay with him for seven days in exchange for 1kg gold per day. John needs to stay there for seven days and also do not want to give the witty man any advance. How can John pay for his seven days stay?

What mathematical symbol can be put between 5 and 9, to get a number bigger than 5 and smaller than 9?

You can see it everyday, But cannot touch it at will. What is it?

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

When my father was 31 I was 8. Now he is twice as old as me. How old am I?

If you drop me I’m sure to crack, but give me a smile and I’ll always smile back. What am I?

I am never scared but became petrified and can’t live in a house but would die to make one. What am I?

Three ants are sitting at the three corners of an equilateral triangle. Each ant starts randomly picks a direction and starts to move along the edge of the triangle. What is the probability that none of the ants collide?