{"id":3492,"date":"2023-11-20T18:02:49","date_gmt":"2023-11-20T23:02:49","guid":{"rendered":"https:\/\/sites.williams.edu\/Morgan\/?page_id=3492"},"modified":"2023-11-20T18:02:49","modified_gmt":"2023-11-20T23:02:49","slug":"palindromic-years","status":"publish","type":"page","link":"https:\/\/sites.williams.edu\/Morgan\/math-chat-archives\/palindromic-years\/","title":{"rendered":"Palindromic Years"},"content":{"rendered":"<p>January 17, 2002<\/p>\n<p>&nbsp;<\/p>\n<p>Last week over four thousand mathematicians gathered in\u00a0<b>San Diego<\/b>\u00a0for the annual joint mathematics meetings. Dave Bayer talked about his work as mathematical consultant to Ron Howard&#8217;s brilliant new movie\u00a0<b>&#8220;A Beautiful Mind,&#8221;<\/b>\u00a0about the schizophrenic Nobel Laureate\u00a0<b>John Nash<\/b>. The movie is based on Sylvia Nasar&#8217;s biography\u00a0<a href=\"http:\/\/www.simonsays.com\/book\/default_book.cfm?isbn=0743226372&amp;areaid=33\">&#8220;A Beautiful Mind,&#8221;<\/a>\u00a0previously recommended here in Math Chat. A new book,\u00a0<a href=\"http:\/\/www.pup.princeton.edu\/titles\/7238.html\">&#8220;The Essential John Nash,&#8221;<\/a>\u00a0contains fascinating autobiographical and mathematical material by Nash, as well as commentary by Harold Kuhn and Nasar.<\/p>\n<p><b>OLD CHALLENGE.<\/b>\u00a0The new year 2002 is a palindrome, the same backwards as forwards. How common are palindrome years?<\/p>\n<p><b>ANSWER.<\/b>\u00a0(Joseph DeVincentis, Toby Gottfried, Sonny Kunnakkat). Currently palindrome years occur at 110-year intervals. The next one after 2002 occurs in 2112. At the end of each millennium, there is an exceptionally short 11-year interval, as we just had from 1991 to 2002 and will have from 2992 to 3003. Long ago, during the two- and three-digit years, there was a palindrome year every 10 or 11 years, as from 989 to 999 or from 88 to 99, with some exceptionally short 2-year intervals, as from 999 to 1001 or from 99 to 101. In the distant future, when we move into the five-digit years, they will generally occur at 100-year intervals, as from 10001 to 10101.<\/p>\n<p>Although the Christian-era calendar has long been the standard throughout the Western world, there are other calendars in use in other parts of the world, most of them also in their four-digit years now. If you consider these years as well, the total frequency of palindrome years is generally multiplied by the number of calendars used&#8211;two or three or more per century.<\/p>\n<p>John M. Sullivan writes: I like to look for palindromes on my car odometer. Of course, the first month or two I owned the car, they were quite frequent, but since then I&#8217;ve gotten used to seeing about one every couple of hours on a long drive. (To increase the fun, I ignore any leading or trailing zeros in the number.) Two weeks ago, during a single four-hour drive, I saw no less than seven plaindromes (including three consecutive ones)! But then last week, I went for a trip twice as long without seeing any. PS: Last October, some noted the palindromic date 10\/02\/2001). Europeans (who put the month first) might note 20\/02\/2002 next month.<\/p>\n<p><b>QUESTIONABLE MATHEMATICS<\/b>. Eric Brahinsky found the following account in an article, &#8220;Noise Meter Doesn&#8217;t Lie,&#8221; by Bonnie Walker in the San Antonio Express-News (28 December 2001):<\/p>\n<p>&#8220;After borrowing the [Digital Sound Level] meter&#8230;, which measures noise in decibels,&#8230; we headed out to a few restaurants to listen&#8230;. The numbers on this listening device, we were told, rise logarithmically, not numerically. I have no idea what this means, except that a rating of 80 is not just 10 percent more than a rating of 70. It&#8217;s actually way higher.&#8221;<\/p>\n<p>Brahinsky comments: Ms. Walker is at least honest about her ignorance of logarithms (though her ploy, familiar among mainstream journalists, of currying readers&#8217; favor by proudly proclaiming her lack of mathematical prowess is a bit tiresome). She needn&#8217;t have stopped there, however, since she seems also to have little idea what percentages mean! Of course, on an absolute linear (&#8220;numerical&#8221;) scale, 80 is some 14 percent higher than 70, not 10 percent higher. Admittedly, decibels are a bit complicated. A sound of 80 decibels has 10 times the physical intensity of one of 70 decibels (that&#8217;s 900% louder), but since the human ear itself seems to respond logarithmically, a person would judge the former sound to be about twice as loud (or 100% louder). Well, I guess either 900% or 100% would be &#8220;way higher&#8221; than either 10% or 14%, so she&#8217;s right about that&#8230;.<\/p>\n<p>Readers are invited to submit more examples of questionable mathematics.<\/p>\n<p><b>NEW CHALLENGE.<\/b>\u00a0What is the loudest sound ever made on earth? the softest?<\/p>\n<p>&nbsp;<\/p>\n<p>Copyright 2002, Frank Morgan.<\/p>\n<hr \/>\n<p>Send answers, comments, and new questions by email to\u00a0<a href=\"mailto:Frank.Morgan@williams.edu\">Frank.Morgan@williams.edu,<\/a>\u00a0to be eligible for<i>\u00a0Flatland\u00a0<\/i>and other book awards. Winning answers will appear in the next Math Chat. Math Chat appears on the first and third Thursdays of each month. Prof. Morgan&#8217;s homepage is at\u00a0<a href=\"http:\/\/www.williams.edu\/Mathematics\/fmorgan\">www.williams.edu\/Mathematics\/fmorgan.<\/a><\/p>\n<p><a href=\"http:\/\/www.maa.org\/pubs\/books\/mch.html\">THE MATH CHAT BOOK,<\/a>\u00a0including a $1000 Math Chat Book\u00a0<a href=\"http:\/\/www.maa.org\/pubs\/books\/quest.html\">QUEST,\u00a0<\/a>questions and answers, and a list of past challenge winners, is now available from the MAA (800-331-1622).<\/p>\n","protected":false},"excerpt":{"rendered":"<p>January 17, 2002 &nbsp; Last week over four thousand mathematicians gathered in\u00a0San Diego\u00a0for the annual joint mathematics meetings. Dave Bayer talked about his work as mathematical consultant to Ron Howard&#8217;s brilliant new movie\u00a0&#8220;A Beautiful Mind,&#8221;\u00a0about the schizophrenic Nobel Laureate\u00a0John Nash. The movie is based on Sylvia Nasar&#8217;s biography\u00a0&#8220;A Beautiful Mind,&#8221;\u00a0previously recommended here in Math Chat. 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