Why must you have the same denominator when adding and subtracting fractions?

Answer 1

you can convert the rational number or fraction to decimal and then add

The answer is the same

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example

1/3 + 1/6

2/6 + 1/6

3/6 =

1/2 or 0.5

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Converting the fraction to decimal and then add.

1/3 + 1/6

0.333333333 + 0.166666667 = 0.5

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In mathmatics there are several ways to solve a problem.

Answer 2

The word "denominator" means "name." In other words, the bottom number on the fraction is it's name. You can add two things with the same name, like cookies and cookies, but not two things with different names, like cookies and bottles.

So when you're adding two fractions, if the denominators are different it's like adding two unlike objects.
4/5 means you have 4 of something called fifths. It has to be added to others with the same name.

Answer 3

The best way to visualize this it take two pieces of paper. On the first paper, fold it into say 4 equal slices. On the second, fold it into say 5 equal slices. Now cut one slice off of each paper. How much paper in total did you cut?? You cut 1/4 + 1/5. This does not equal 2/4 or 2/5, it is 9/20.

Answer 4

its not impossible just makes it easyier 1/2 + 1/3 is harder to do then 3/6 + 2/6 which is 5/6

Answer 5

well one its easier to do when their the same and were told to do it that way but if you dont want to change the denominator you could always just turn it into a decimal

Answer 6

Because it's imposibe to add or subtract them that way.