A student was simply solving a routine word problem of Class 10 when he noticed something strange. A tiny shortcut appeared to give the answer instantly. The class was impressed. Then someone asked the question that turns school mathematics into mathematical investigation. The Original Question : A man bought some pens for ₹5760. If each pen had cost ₹8 less, he would have received 10 more pens for the same amount. Find: The original cost of each pen The number of pens bought originally Most students solved it algebraically. Let the original cost per pen be p. Then the original number of pens is: 5760/p If the price decreases by ₹8, the new price becomes: p-8 And the new number of pens becomes: 5760/(p-8) Since he gets 10 more pens: (5760/p) +10 = 5760/(p-8) 5760 ( p − 8 ) + 10 p ( p − 8 ) = 5760 p . 5760p-46080+10p^2-80p=5760p. 10 p^ 2 − 80 p − 46080 = 0. p^ 2 − 8 p − 4608 = 0. Solving gives: p = 72 Original cost = ₹72 Original number of pens = 5760/72 = 80 At this stage, it ...