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Congratulations! You clicked on the link to go to this instructable! (that was obvious.....) Anyway, this hopefully will teach you the basics of adding fractions. Well, here's Fraction 101.
The top number is the numerator and the bottom number is the denominator. To add fractions, the denominators (bottom numbers) have to be the same. One easy way to remember that the denominator is the bottom number is to remember that it's the one "Down under" (since they both begin with D you're all set).
Here's an example: 3/7 & 5/7 can be added, but 4/7 & 4/9 cannot.
Well, they can, but a few changes have to be made. We'll go over these later.
The top number is the numerator and the bottom number is the denominator. To add fractions, the denominators (bottom numbers) have to be the same. One easy way to remember that the denominator is the bottom number is to remember that it's the one "Down under" (since they both begin with D you're all set).
Here's an example: 3/7 & 5/7 can be added, but 4/7 & 4/9 cannot.
Well, they can, but a few changes have to be made. We'll go over these later.
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Signing UpStep 1Adding Simple Fractions
Adding simple fractions
Here's an example of adding a fraction.
1/4 + 2/4 = _
First, check to see if the denominators, the bottom numbers, are the same. If they are, you're lucky because the fractions are easy to add. To add fractions with common denominators, all you have to do is add the two numerators leaving the denominator the same.
In this example you'd add 1 + 2 = 3 which will be the numerator of our answer.
So, 1/4 + 2/4 = 3/4. Note that we don't add the denominator. Our added fraction will end up being 3/4.
The reason for this is that a fraction is basically a division problem. When you add them you add the two numerators together to make one division problem, or a fraction. You can do this easily when the denominators are the same.
For example, think of a pie (not pi):
- If you divide the pie into 4 pieces, each piece is one of four pieces, or 1/4 of the pie. 2/4 would be two of the four pieces of the pie, etc. (see first two pictures below)
- If you give one person 1/4 and another 2/4 you've given away three of four pieces of the pie, or 3/4 and you have 1/4 of the pie left. (see picture below)
- If you add the 1/4, the pie you have left, and the 3/4, the amount of pie you gave away, you get one, because adding 1/4 and 3/4 gives you 4/4 or a whole pie!
- If the numerator and denominator of a fraction are the same, then it equals 1. Like 2/2, which is 2 halves, or one whole.
Here's an example of adding a fraction.
1/4 + 2/4 = _
First, check to see if the denominators, the bottom numbers, are the same. If they are, you're lucky because the fractions are easy to add. To add fractions with common denominators, all you have to do is add the two numerators leaving the denominator the same.
In this example you'd add 1 + 2 = 3 which will be the numerator of our answer.
So, 1/4 + 2/4 = 3/4. Note that we don't add the denominator. Our added fraction will end up being 3/4.
The reason for this is that a fraction is basically a division problem. When you add them you add the two numerators together to make one division problem, or a fraction. You can do this easily when the denominators are the same.
For example, think of a pie (not pi):
- If you divide the pie into 4 pieces, each piece is one of four pieces, or 1/4 of the pie. 2/4 would be two of the four pieces of the pie, etc. (see first two pictures below)
- If you give one person 1/4 and another 2/4 you've given away three of four pieces of the pie, or 3/4 and you have 1/4 of the pie left. (see picture below)
- If you add the 1/4, the pie you have left, and the 3/4, the amount of pie you gave away, you get one, because adding 1/4 and 3/4 gives you 4/4 or a whole pie!
- If the numerator and denominator of a fraction are the same, then it equals 1. Like 2/2, which is 2 halves, or one whole.
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I only have one small criticism:
It is not good practice to write mixed fractions without the addition operator. A mixed fraction is a sum, and it should be written as such, e.g.
3 + 1/2
The notation:
3 1/2
is confusing because there is another convention that says putting two expressions side by side like that means multiplication; i.e.
3 1/2 = 3 * 1/2 = 3/2
This may seem nit-picky to many of you, but this is math after all. It is good to be clear about what your expressions mean.
See also:
http://mathworld.wolfram.com/MixedFraction.html