Rearranging the terms
We can rearrange the terms and rewrite this equation as
distance = (63360 * inch * 1*foot * 1 * mile)/(12*inch*5280*foot)
Canceling like terms
Canceling out like terms in the numerator and denominator leaves us with
distance = (63360*mile)/(12*5280)
Doing the arithmetic, we get
distance = 1*mile
(Obviously, I started out with a set of numbers that were designed to cause the final answer to be one mile, but that was simply for convenience.)
There you have it
You have seen a detailed procedure for converting from a distance expressed in paces (for a specific individual) to the same distanceexpressed in miles. Obviously, once you understand the overall procedure, you could omit and/or combine some of the steps to simplify the process.
Using JavaScript to convert units
Let's write, execute, and analyze a script that solves the same problem.
The objective of the script is to convert a distance of 2112 paces to a distance in miles where it is given that
- 100 paces = 3000 inches
- 12 inches = 1 foot
- 5280 feet = 1 mile
Please copy the code from Listing 1 into an html file and open the file in your browser.
Listing 1 . Convert from paces to miles.
>!-- File JavaScript01.html ------------------------------>>html>>body>>script language="JavaScript1.3">var d = 2112 //distance, units = paces
document.write("d = " + d + " paces" + "<br/>")
var d2 = 3000 //distance, units = inchesvar d3 = 100 //distance, units = paces
var f1 = d2/d3 //factor, units = inches/pacedocument.write(
"f1 =" + f1 + " inches/pace" + "<br/>")
//pace*inch/pace = inchvar d = d *f1 //distance, units = inches
document.write("d = " + d + " inches" + "<br/>")
var f2 = 1/12 //factor, units = feet/inchdocument.write(
"f2 = " + f2 + " feet/inch" + "<br/>")
//inch*feet/inch = feetvar d = d *f2 //distance, units = feet
document.write("d = " + d + " feet" + "<br/>")
var f3 = 1/5280 //factor, units = miles/footdocument.write(
"f3 = " + f3 + " miles/foot" + "<br/>")
//feet*mile/feet = milevar d = d *f3 //distance, units = miles
document.write("d = " + d + " mile" + "<br/>")
//Now reverse the process using reciprocals//(pace/inch)*(inch/foot)*(foot/mile) = pace/mile
var f4 =(1/f1)*(1/f2)*(1/f3) //factor, units = paces/miledocument.write(
"f4 = " + f4 + " paces/mile" + "<br/>")
//miles*paces/mile = pacesvar d = d *f4 //distance, units = paces
document.write("d = " + d + " paces" + "<br/>")
document.write("The End")>/script>>/body>>/html>
Screen output
When you open the html file in your browser, the text shown in Figure 5 should appear in your browser window.
| Figure 5 . Screen output for Listing #1. |
|---|
d = 2112 paces
f1 =30 inches/paced = 63360 inches
f2 = 0.08333333333333333 feet/inchd = 5280 feet
f3 = 0.0001893939393939394 miles/footd = 1 mile
f4 = 2112 paces/miled = 2112 paces
The End |
Discuss the output first
Let's begin our discussion with the screen output shown in Figure 5 and then go back and examine the code that produced that output.
Figure 5 begins with a distance (labeled d ) expressed in units of paces. The value is 2112 paces, which is the distance from your home to your school discussed earlier.