-----Original Message----- From: [EMAIL PROTECTED] <[EMAIL PROTECTED]> To: U.S. Metric Association <[EMAIL PROTECTED]> Date: March 20, 2002 15:54 Subject: [USMA:18935] RE: Just 2 rules
>> I request everyone kindly to use these 2 rules when >> talking in metric units to people in USA. >> >> 1. Try to round the units to easy numbers like 60, >> 100, 2500 instead of saying 62, 104, 2521, etc. > >I would also like to point out that where possible, I use multiples of >1, 2 and 5. Thus 10, 20, 50, 100, 200, 500 etc. > >These are [near] equal intervals on a logarithmic scale and suitable for >large dynamic ranges. These intervals are also used as coins in many >currencies and the combinations work well. Apart from that, I agree with the logic of 1,2,5, [10] etc. Duncan > >People appear to be naturally inclined to repeated divisions of two. >This is fine for natural human activities like cutting cakes. > >So non-decimal people are happy with halves and decimal people are happy >with multiples of 5 (5, 50, 500 etc). The trouble is when people go on >to divide by two again you get quarters (25, 250, 2500) which can appear >to be ok, but you also get 2.5 which is not really ok. Even worse you go >on to get things like eighths (1.25, 12.5, 125). The conversion of old >quarter dollars and inch fractions (starting with what looks fractional >- 25.4 mm) reinforces some of this fractional thinking. > >The problem is thinking in fractions of the next largest unit (e.g. >quarters) and then translating into decimal, rather than thinking >upwards in whole multiples of the next smallest unit in each decade. > >If you use 1, 2, and 5 you also get the benefit that the intervals and >the numbers of intervals are the same. So you can have 2 intervals >separated by 5 units (5, 10) or 5 intervals separated by 2 units (2, 4, >6, 8, 10). > >I recommend this and would welcome comments. >-- >Terry Simpson >Human Factors Consultant >[EMAIL PROTECTED] >www.connected-systems.com >Phone: +44 7850 511794 > >
