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Date: 11/10/97 at 20:49:37
From: Catherine Morrissey

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
_______

```

```
Date: 11/11/97 at 12:25:20
From: Doctor Mike

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

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

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/
```
Associated Topics:
Elementary Fractions

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