The Online Encyclopedia of Integer Sequences calls it the "Hyperinflation Sequence for Banknotes". http://www.research.att.com/~njas/sequences/A051109
The following may be obvious to some people, but it's worth stating: I always just assumed they used the 2's and 5's because these numbers are the factors of 10. Since we want to make notes and coins in nice, round powers of ten for obvious reasons, using 2 and 5 as the only other factors ensures that most denominations are evenly divisible by all the denominations before them. (In fact, the only exception is that a "2*10^x" currency does not divide evenly into a "5*10^x" currency for any integer x). This would make it easier to pay someone the right amount, or the right change, when your selection of bills or coins is limited. --- Pat Naughtin <[EMAIL PROTECTED]> wrote: > Dear All, > > Can anyone help me with a name and a history for this series of numbers. > > 0.05, 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, and 500, > > It is used in many of the world's currencies Australia, for example, > has coins of 5 cents, 10 cents, 20 cents, and fifty cents and then > notes of 1 dollar, 2 dollars, 5 dollars, 10 dollars, 20 dollars and > then 50 dollars and 100 dollars. > > I also think that it also has some applications in engineering to > reduce for example the range of bolt or screw sizes in manufacturing. > > Cheers, > > Pat Naughtin > > PO Box 305 Belmont 3216, > Geelong, Australia > Phone: 61 3 5241 2008 > > Metric system consultant, writer, and speaker, Pat Naughtin, has > helped thousands of people and hundreds of companies upgrade to the > modern metric system smoothly, quickly, and so economically that they > now save thousands each year when buying, processing, or selling for > their businesses. Pat provides services and resources for many > different trades, crafts, and professions for commercial, industrial > and government metrication leaders in Asia, Europe, and in the USA. > Pat's clients include the Australian Government, Google, NASA, NIST, > and the metric associations of Canada, the UK, and the USA. See > http://www.metricationmatters.com/ > for more metrication information, contact Pat at [EMAIL PROTECTED] > or to get the free 'Metrication matters' newsletter go to: > http://www.metricationmatters.com/newsletter/ > to subscribe. > > ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ
