Percent Bloopers

A delightful book by E. Barbeau opens with this example:

How to get drunk and rich at the same time

The column Money angles: where else to invest? by Andrew Tobias in the May 17, 1993, issue of Time offers this advice for improving your financial worth:

Buy staples in bulk when they're on sale ... Consider a family that buys one bottle of wine each week. With the 10% discount many stores offer on wine by the case, they would be saving 10% every twelve weeks - more than 40% a year, tax free and largely risk free.

One can in fact do better; increase your consumption to one case per month and save 120% over a year, thus qualifying for a 20% payback from the merchant. (Submitted by Larry Zeitel of Loras College in Dubuque, IA.)


  1. E. J. Barbeau, Mathematical Fallacies, Flaws, and Flimflam, MAA, 2000
  2. A. K. Dewdney, 200% of Nothing, John Wiley & Sons, Inc., 1993

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  • What Is Percent?
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  • Correlation and Causation: Misuse and Misconception of Statistical Facts
  • Benford's Law and Zipf's Law
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