The E-Sylum:  Volume 10, Number 47, November 18, 2007, Article 27

STRANGE BUT TRUE?  MATHEMETICIAN SAYS CENT'S HEADS SIDE SMALLER THAN TAILS

Bob Knepper of Anaheim, CA writes: "The last E-Sylum
mentioned the new book "A Guide Book of Lincoln Cents" by
Q. David Bowers.  I recently encountered some information
about current U.S. cents that was surprising, at least
to me, as I collected them for many years.  Apparently the
tails or Memorial side of a U.S. cent is about 0.002 inches
larger in diameter than the heads side, according to the
book 'The Heart of Mathematics' by Edward B. Burger &
Michael Starbird.

"The proof or test is to line up a fairly large number of
cents, all face up and tight together, against a ruler and
measure their length.  Then alternate heads and tails and
measure again.  The alternating tapers will nest together
yielding a slightly smaller measurement.  With 30 cents,
the difference is only 0.030 = 1/32 inch but I've tried it
four times with different cents and gotten the same result
each time.

"This only determines that there is a difference.  The book
says spinning (not flipping) a cent on a smooth surface and
determining how it lands indicates that the tails side is
larger.  I got the same result but only for 30 trials.  It
would take a lot of trials to be conclusive or to win
significant money.

"A letter from the U.S. Mint said they have no information
about the edge details of cents."

[OK gang, who's game to put this to the test?  Few of us are
patient enough to flip coins over and over, but the line-up
test is fast and straightforward.  Anyone have enough new
cents handy to give it a try?  Let us know the result.
Anyone care to try it with other U.S. coins, or coins of
other countries? -Editor]

  Wayne Homren, Editor

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