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### Comparing Fraction Size: Two Methods

```
Date: 10/24/2001 at 00:52:28
From: Megan
Subject: Fractions

What fraction is greatest?

5/13     2/5     7/15

me?

Thank you!
```

```
Date: 10/24/2001 at 12:06:32
From: Doctor Sarah
Subject: Re: Fractions

Hi Megan - thanks for writing to Dr. Math!

You can find a common denominator by multiplying together the
denominators of your fractions. For example, try 13 * 15 = 195 (you
don't need to use the 5 because anything divisible by 15 will also be
divisible by 5).

You know that 195 is divisible by 13 and 15 (because those are the two
numbers you multiplied together to get it), and by 5 because 195 ends
in a 5. Now convert the numerators so you have equivalent fractions:

5/13 = 75/195
2/5 = 78/195
7/15 = 91/195

So 7/15 is the greatest.

But sometimes it's easier just to convert your fractions to decimals
by dividing the numerators by the denominators:

5/13 = .38461538461538
2/5 = .4
7/15 = .46666666666666 (repeating forever)

Here you can see that each fraction is larger than the one before it.

Does this help?

- Doctor Sarah, The Math Forum
http://mathforum.org/dr.math/
```
Associated Topics:
Elementary Fractions

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