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Here's a puzzle I just heard and while I know that this reasoning is fundamentally wrong, I can't explain why:

  1. Three people bought a dish for, say, 25\$ and paid 30\$
  2. The waiter didn't want to divide 5 by 3, so he took 2\$ for himself and gave 1$ to each of the clients
  3. Each of them seems to have spent 9\$, but 9\$ x 3 = 27\$, not 28. What happened to this one dollar?
d33tah
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    http://en.m.wikipedia.org/wiki/Missing_dollar_riddle – Alex R. Sep 06 '14 at 16:48
  • @AlexR. I wish you posted the link as an answer, I would have accepted it. – d33tah Sep 06 '14 at 16:59
  • More duplicates: http://math.stackexchange.com/questions/656047/where-is-the-lost-dollar http://math.stackexchange.com/questions/656047/where-is-the-lost-dollar http://math.stackexchange.com/questions/480195/general-and-simple-math-problem – MJD Sep 06 '14 at 20:41

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Expenditure of customers: $$ 30 \text{ (initial payment})-\color{green}{3} \text{ (change})=\color{teal}{27}. $$ Income of restaurant: $$ 30-\color{red}{2} \text{ (waiter's stolen amount})-\color{green}{3}\text{ (change to customers})=\color{blue}{25}. $$ Income of waiter: $$ \color{red}{2}, $$ which is just the amount he stole.

Total income $=\color{red}{2}+\color{blue}{25}=\color{teal}{27}=$ total expenditure. So no inconsistency here.

Kim Jong Un
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