Subtracting Fractions

Date: 9/6/96 at 22:30:53
From: Anonymous
Subject: Visualization of Subtracting Fractions 

How do I solve 3/4 - 1/2? I tried drawing a circle and marking off the 
area, but that didn't work.

Date: 9/13/96 at 13:42:42
From: Doctor Mike
Subject: Re: Visualization of Subtracting Fractions 

Hi,
  
Let me see if I understand your question. I assume that the circle 
comes into it when you visualize fractions as slices of a pie.
  
Just working with the numbers you can get some benefit by seeing 
that 1/2 is the same as 2/4 so the original problem can be rewritten 
as 3/4 - 2/4.  With the denominators the same it is an easier problem.  
By the same reasoning which tells you that 3 apples minus 2 apples 
is 1 apple, you have 3 fourths minus 2 fourths is 1 fourth, or 
3/4 - 2/4 = 1/4 .
  
When it comes to pie, if you start with 3/4 of a pie and remove half a 
pie (= 2/4) then you have 1/4 left.  That is, you have a nice generous 
piece left for me!  Yummmmmmmm.
  
I hope this helps.    

-Doctor Mike,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/