Hmm... lets see how good are the members of this cool community. I will start a thread in which people can ask fun puzzles which have an obvious solution and other people can try answering them along with the logic furnished with the solution. After all we need something to oil our rusty cogs up above...eh.. I'll start:
If a man earns Rs 20 on first day and spends Rs 15 on second day ,and earns Rs 20 on third day and spends Rs 15 on fourth day and goes on on which day he will be having Rs 60. HINT (This is not as easy as it looks)