Today after a long interval I'm solving math puzzle that I used to enjoy solving by picking up the problem from one website,which shows some math puzzle every week.I was strong especially at geology and once I solved the difficult puzzle that can never be thought out by any one without using the method we learn after junior high-school class.Yes,this website submit only puzzles that can be solved with elementary knowledge.However,as the time goes by and I get a little older,I realized that I also become good at solving the problem using number rather than figure.I could hardly imagine that after the age of 40 I could still make advance in such skill!This also became my significant step to start showing interest in computer software technology.It must seem strange that I semiconductor hardware engineer have had few knowledge about software which I also have felt ashamed,but now things is being improved.As the old saying goes,Great talent mature late.

P.S.This week's math problem is very difficult that so far can be solved.The auther must have had hard time in thinking out this week's puzzle since it's the memorableing 500th puzzle of that website!