# Why do fractions need to have a common denominator before you add or subtract them?

asked Jan 5, 2012

When fraction do not have a common denominator, you are trying to add different sized pieces.  Remember that the smaller the denominator the larger the piece.

So, to add or subtract fractions the pieces we are using must be the same size.

answered Jan 5, 2012 by Level 10 User (51,360 points)
If you think of two pies, one cut into 3 pices and the other cut into 8 pices, if you want to take a slice away from each of them it would be unfair because the pie cut into 3 slices is not proportional to the one cut into 8 pices. This is how I think about it .
answered Jan 5, 2012 by Level 5 User (13,780 points)
because it isNT posible now get out maiii face u ugly
answered Jan 8, 2013 by anonymous
because you do
answered Jan 10, 2013 by anonymous
ou can not add diffrent denomanators together with fractions you NEED a least common denomanator
answered Jan 14, 2013 by anonymous
Get off the Internet and rely on your Brain
answered Feb 14, 2013 by anonymous
UYGUIYTTUYTUGYFTYRYFYTRY
answered Feb 20, 2013 by anonymous

**** off pussys suck my *****

answered Feb 23, 2013 by anonymous
i'm not trying to be mean, but can't you just ask somboby, look it up on a another website, or just do nothing about it. if you're crying, i'm veryyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy sorry. i am to sad to tell you the anserws too.
answered Feb 26, 2013 by anonymous
The denominator tells you what size parts you are adding or subtracting.  The parts must be the same size when you add or subtract.
answered Mar 10, 2013 by anonymous

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