Date: 11/10/97 at 20:49:37 From: Catherine Morrissey Subject: Addition of Fractions Hi. I have been having some problems with addition of fractions. I am kind of worried because everyone in my math class gets it but me! The first problem I have is 4 2/3 + 3 1/6. I tried solving it by setting it up like this 4 2/3 + 3 1/6 _______ but it didn't help. I just don't know how. Please help me!
Date: 11/11/97 at 12:25:20 From: Doctor Mike Subject: Re: Addition of Fractions Dear Catherine, Probably there are others in your math class who don't get it, but they just keep quiet about it. It can be sort of hard to get the hang of fraction addition. Here is the way I think your teacher has in mind for you to do this. If you make both fractions have the same denominator, then the problem looks like this : 4 4/6 + 3 1/6 _______ 7 5/6 The easy part is adding the whole numbers together to get 7, and then it's easy to add up the fractional parts because they are both the same kind. While we are talking, why don't I answer another question that is certain to come up as you continue your homework on this. Look at this example, which is similar to your other problem. 4 2/3 + 3 5/6 _______ The first thing to do, as before, is to change whatever is necessary to get the fractions to have the same denominator. [By the way, that is often called the COMMON denominator, not because it is "common" like "ordinary," but because it is "common" as in "the same."] 4 4/6 + 3 5/6 _______ 7 9/6 Your teacher will NOT want you to leave the answer in this form. There are two reasons why. One reason is that 9/6 can be reduced to the simpler fraction 3/2, and we like to make fractions as simple as possible in writing answers. Now, what's wrong with 7 3/2 as an answer? Only that we like to have the fraction part be a fraction between zero and one. Since 3/2 is just "one and one half," we can include the "one" in the whole number part, getting 8 1/2. See? I hope these examples help. Write back if you have more questions. -Doctor Mike, The Math Forum Check out our web site! http://mathforum.org/dr.math/
Search the Dr. Math Library:
Ask Dr. MathTM
© 1994-2013 The Math Forum