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Riddle (simple arithmetic problem/illusion)

Three men go to a shop and take some food which is cost $25. Waiter came and gave them bill. <pre>Each of them gave $10. So, waiter take total

Waiter came back with
$5</pre>. Three men took <pre>$1+$1+$1
and they decide to gave rest $2 to waiter. Now if we calculate the above thing then it should look like this: </p> <pre> Man A total spend $10 - $1 = $9 Man B total spend $10 - $1 = $9 Man C total spend $10 - $1 = $9 Three men Total = $27 and waiter take = $2 So , three men total + waiter = $27 + $2 = $29 !!!! Where is another Dollar gone! Can anybody please explain it for me please?


marked as duplicate by Hans Lundmark, user3302, Aryabhata, Rahul, Jonas Meyer Feb 5 '11 at 8:30

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  • 5
    $\begingroup$ The erroneous assumption is that the total money involved should add up to the money initially brought into play, i.e., the 30 dollars. If you think about it carefully, it makes total sense: Three men total is 27. The bill was 25 and they gave 2 additional to the waiter, so they paid 27 and the waiter obtained 27. $\endgroup$ – Lagerbaer Feb 4 '11 at 19:26
  • $\begingroup$ I think the appropriate tag should be accountancy. This is where double-entry bookkeeping shows its usefulness. $\endgroup$ – Raskolnikov Feb 4 '11 at 19:51
  • $\begingroup$ @accountancy thank you for your advice. i search for "accountancy" but did not find the tag! as you can see i am pretty new in this site and do not have the permission to create a new tag. $\endgroup$ – enam Feb 4 '11 at 19:59
  • 3
    $\begingroup$ This is a duplicate; see math.stackexchange.com/questions/15524/…. $\endgroup$ – Hans Lundmark Feb 4 '11 at 20:02
  • 1
    $\begingroup$ See here and here for an explanation: spikedmath.com/334.html spikedmath.com/335.html $\endgroup$ – Myself Feb 4 '11 at 21:08

The wrong numbers are added and subtracted. It should be:

The men pay 30

The waiter gives 3 back, so the men paid 27 and the waiter got 27

The food was 25, so the waiter can keep 2 dollars.

  • $\begingroup$ total bill is 25 dollar how can waiter give 3 dollar back? $\endgroup$ – enam Feb 4 '11 at 19:30
  • 2
    $\begingroup$ The total is indeed 25, but the men paid 30. The waiter should give 5 back, but keeps 2 of these 5, thus giving 3 back. $\endgroup$ – Patrik Feb 4 '11 at 19:35

The $\$27$ includes the $\$25$ they paid for food, plus the $\$2$ to the waiter. They pocketed the other three dollars.


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