Find The Next Number in the series:

12 13 15 17 111 113 117 119 123 ?

What is the centre of gravity?

100 prisoners are stuck in the prison in solitary cells. The warden of the prison got bored one day and offered them a challenge. He will put one prisoner per day, selected at random (a prisoner can be selected more than once), into a special room with a light bulb and a switch which controls the bulb. No other prisoners can see or control the light bulb. The prisoner in the special room can either turn on the bulb, turn off the bulb or do nothing. On any day, the prisoners can stop this process and say "Every prisoner has been in the special room at least once". If that happens to be true, all the prisoners will be set free. If it is false, then all the prisoners will be executed. The prisoners are given some time to discuss and figure out a solution. How do they ensure they all go free?

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

Count the number of balls in picture below:

On one occasion, A Boy collects 71 rupees in form of 20 paise and 25 paise. He collects a total of 324 coins.

Can you tell me how many 20-paisa and 25-paisa he got?

What goes through cities and fields, but never moves?

How many bananas can you eat if your stomach is empty?

What is so fragile that saying its name breaks it?

Can you place three balls such that the equation shown in the picture holds true?