THE MISSING COIN

three men go to a restaurant to have dinner. the owner of that restaurant comes up to the three men and offers then to eat as much food as they like for only 30 $. the three men share the cost and agree to pay 10$ each to the owner. when the owner goes back to his office, he realizes that today had a special and that the three man could eat as much as they liked for only 25$. And so the honest owner gives 5 $ to the server so he could give that many back to the men. The server didn't know how he could divide 5$ into three equal parts. So the server decides to keep 2$ for himself and gives 1$ to each of the three men. the three man had initially paid 10$ and now received 1$ back as if they had only paid 9$ each. 9$ times 3 men equals 27$, plus the 2 dollars that the sever kept equals 29$. After all, where did that 1 missing dollar go???