Drexel dragonThe Math ForumDonate to the Math Forum

Ask Dr. Math - Questions and Answers from our Archives
_____________________________________________
Associated Topics || Dr. Math Home || Search Dr. Math
_____________________________________________

Multiplying a Fraction by a Decimal


Date: 9/5/96 at 13:8:48
From: Glenn Hill
Subject: Fraction Times a Number

How do I simplify and multiply:

  40    
 ----- x 78.5
  360


Date: 9/6/96 at 4:20:55
From: Doctor Mike
Subject: Re: Fraction Times a Number

Hi Glenn,
  
There are several ways to do this.  If you have a calculator, you 
could do  40/360  first, and then multiply that by 78.5 .

If you are doing it by hand, then the easiest way is to first reduce 
the fraction to lowest terms.  The numerator 40 and the denominator 
360 are both multiples of 10, so you could divide both numerator and 
denominator by 10 to get the equivalent fraction 4/36 .  Since 4 times 
9 is 36, this fraction is equivalent to 1/9 .  

Your original problem is now 
  
    1   
   --- x 78.5
    9   
  
That is the same as 78.5/9 which you can do on paper with long 
division.  Either way the answer is an infinitely repeating decimal  
8.722222222... .  A good approximate value is 8.722.
  
I hope this helps.

-Doctor Mike,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/   
    
Associated Topics:
Elementary Fractions
Middle School Fractions

Search the Dr. Math Library:


Find items containing (put spaces between keywords):
 
Click only once for faster results:

[ Choose "whole words" when searching for a word like age.]

all keywords, in any order at least one, that exact phrase
parts of words whole words

Submit your own question to Dr. Math

[Privacy Policy] [Terms of Use]

_____________________________________
Math Forum Home || Math Library || Quick Reference || Math Forum Search
_____________________________________

Ask Dr. MathTM
© 1994-2013 The Math Forum
http://mathforum.org/dr.math/