23 Apr
2014
23 Apr
'14
4:24 p.m.
Total off-the-wall guess: In old financial conventions, some of which persist to this day, a year is reckoned as 360 days (which I guess simplified the arithmetic), and so one quarter of a year is 90 days. --Dan On Apr 23, 2014, at 3:13 PM, Bill Gosper <billgosper@gmail.com> wrote:
R. Weyhrauch notes that http://digital.library.pitt.edu/cgi-bin/t/text/pageviewer-idx?c=darltext;cc=... (a document older than the dollarsign) prescribes a bunch of tariffs in 90ths instead of %. I thought I had a mathematical motivation, but was wrong. NeilB thought of a historical, rather than mathematical explanation, but it seems decreasingly plausible.
Can someone at least provide a good guess?