Bill & azll: >.....having solved for y, one can now convert to decimal. WHY, is this Metric....NOT decimal either? What a way to THINK METRIC!!!!!
No offences, please. Brij Bhushan Vij (MJD 2455066)/1361+D-243W34-05 (G. Saturday, 2009 August 22H15:24 (decimal) EST Aa Nau Bhadra Kritvo Yantu Vishwatah -Rg Veda Jan:31; Feb:29; Mar:31; Apr:30; May:31; Jun:30 Jul:30; Aug:31; Sep:30; Oct:31; Nov:30; Dec:30 (365th day of Year is World Day) My Profile:http://www.brijvij.com/bbv_2col-vipBrief.pdf HOME PAGE: http://www.brijvij.com/ ******As per Kali V-GRhymeCalendaar***** "Koi bhi cheshtha vayarth nahin hoti, purshaarth karne mein hai" Contact # 001 (201) 675-8548 From: [email protected] To: [email protected] Subject: [USMA:45689] RE: Decimal fractions or common fractions? (Metric or not?) Date: Sat, 22 Aug 2009 11:02:25 -0700 Bill: It's much simpler than that: 21y x 8 = 1 168y = 1 y = 1/168 Your second and third lines seem to be annotations, rather than part of the process. Also, no fractions are involved (above) other than in the solution, so the issue of decimal vs. fractions doesn't really come up. And, as you've indicated, having solved for y, one can now convert to decimal. Bill Bill Potts WFP Consulting Roseville, CA http://metric1.org [SI Navigator] From: [email protected] [mailto:[email protected]] On Behalf Of Bill Hooper Sent: Saturday, August 22, 2009 10:38 To: U.S. Metric Association Subject: [USMA:45688] Decimal fractions or common fractions? (Metric or not?) On Aug 19 , at 8:43 AM, Stephen Davis wrote: I do believe that algebra sums are going to particularly difficult to work out using decimal fractions. For instance a linear equation such as: 21y x 8 = 1 ...is going to take some monumental working out using decimals. 21y x 8 = 1 1 / 8 =1/8 1/8 / 21 = 1/168 y = 1/168 I see no difficulty with such an algebra problem. I would solve it just about like Stephan did, BUT ... If it were part of a physics or other real world problem (rather than a "pure", numerical algebraic problem), I would add one final step. That step would be to divide out the ratio "1/168" to get: 0.00595 (Note that I immediately rounded off appropriately*. The long calculator calculation gives 0.005952381 ... etc. I would never even bother to look at all those extra digits, but would just note and write the rounded value. That might not be wise for a pure algebra problem but it is certainly appropriate in the real world of "real numbers" with finite precision.) Then, if it is a physics problem, the answer would (almost surely) be a measurable quantity and therefore would (almost surely) have units. If the quantity is a length, the units might be metres, for example. That would then allow me to simplify the number by changing from metres to millimetres (or even micrometres), thus: 0.00595 m = 5.95 mm (= 5950 µm). In a purely algebraic problem, I would agree that one of the reasons for keeping the answer in ratio form (1/168) is the fact that, without units, there is no other way to express the answer in compact form. But real problems with real numbers are a different story. So I agree that expressing such numbers in ratio form might be better than decimal form in some cases (algebraic). However, I continue to think that one should not teach common fractions and all the related arithmetic (adding them, dividing them, finding least common denominators, etc., etc.) early in students' education. That should wait until the students take an algebra course (usually high school, not elementary or middle school). In the elementary grades, students should be introduced ONLY to decimal fractions and decimal arithmetic (along with decimal based metric units of measure). Bill Hooper 1810 mm tall Fernandina Beach, Florida, USA -------------------------------------------------- *The degree of rounding off would depend on the precision of the numerical values in the original problem (the "21", the "8" and the "1"). I have rounded the answer to three significant figures as is common for ordinary measures or where the exact degree of precision is unknown or unimportant. ========================== SImplification Begins With SI. ========================== _________________________________________________________________ With Windows Live, you can organize, edit, and share your photos. http://www.windowslive.com/Desktop/PhotoGallery
