Well, 1) I didn't realize we were having a contest 2) The exact figure already appears as footnote 23 in Appendix B of NIST SP811 3) There are many calculator apps for PCs that use double precision floating point and can do the multiplication directly and explicitly (as can Excel)
While it is more digits than would ever be needed, I do think it is useful to have "exact" values (or at least the full precision of the math processor) in computerized conversion routines. It makes little sense to store the "wrong" value when you can store the "right" value as a compiler constant. ________________________________ From: "mechtly, eugene a" <[email protected]> To: U.S. Metric Association <[email protected]> Cc: "mechtly, eugene a" <[email protected]> Sent: Fri, May 10, 2013 6:08:13 PM Subject: [USMA:52755] Numerical Verification of lbf and lbm with 9.80665 in Newton's Second Law Why has no person yet volunteered a confirmation of the exact arithmetic of lbf and lbm in f = m x 9.80665? Do the exact numerical values simply have two many necessary digits to be multiplied exactly by most of us? Hint: Use (a + b) x (c + d) where the numbers ( ) with "too many digits" are expressed as sums, and each part of each sum is initially expressed in exponential form. Then, this exercise becomes tractable on many inexpensive digital calculators. Who will be the first to confirm the exact fit of lbf and lbm (as *defined* numerically) with Newton's Second Law? Or, would most of you simply prefer to trash all that is non-SI? (a perfectly respectable attitude) Eugene Mechtly
