If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

using four eights (8) and a one (1) and one mathematical symbol , create the number 100

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?

Which Burger Is Different in below image?

If a boy blows 18 bubbles,
Then pops 6 eats 7 and then
He pops 5 and blows 1.
How many are left?

If a shopkeeper can only place the weights on one side of the common balance. For example, if he has weights 1 and 3 then he can measure 1, 3 and 4 only. Now the question is how many minimum weights and names of the weights you will need to measure all weights from 1 to 1000? This is a fairly simple problem and very easy to prove also.

Look at the picture and find out which square is not linked with any of the other squares.

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

If an earthquake is 1 point higher on the Richter Scale than another earthquake which is actually 10 times stronger, how much stronger would an earthquake be if it was just half a point higher on the Richter scale?

10+10 and 11+11 can give you the same answer.

Explain how?