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Worried about adding and subtracting fractions? Never fear. It's so easy that it will only take up a fraction of your time: just use multiplication...
Adding and Subtracting Mixed Numbers 5069 Views
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Description:
Come on, mixed numbers. We have to do all these steps, and there's no promise that we'll end up with an easier number? Actually, it's not that bad. As long as you have the same denominator (which you can find using the least common denominator), you can add up the numerators and get your final answer.
Transcript
- 00:00
Adding and subtracting mixed numbers. A la shmoop.
- 00:04
There's been an accident, but we're going to need everyone to remain calm.
- 00:09
It seems that someone -- we're not naming names...
- 00:12
caused a spill in the number factory. Now, instead of nice, round numbers, we've
- 00:16
got an outbreak of mixed numbers on our hands. We're going to have to quarantine the area
Full Transcript
- 00:21
until we take care of this situation. Maybe by adding them together, we can get
- 00:25
our old numbers back again, and all of us can go on our merry way.
- 00:30
When it comes to adding or subtracting these suckers, we have to fiddle with them first.
- 00:34
Let's say we want to add the following: Four and three-fourths plus one-sixth.
- 00:39
We're not sure if doing so will give us one of our whole numbers, but there's only one
- 00:41
way to find out... First, we change each mixed number into an
- 00:43
improper fraction. Don't worry -- we won't offend anyone.
- 00:48
Nineteen-fourths plus one-sixth The LCM, or Least Common Multiple, of four
- 00:55
and six is twelve, so we need to convert each fraction to one with a denominator of twelve.
- 01:02
Fifty-seven twelfths plus two twelfths. We can use these numbers because nineteen
- 01:06
fourths is the same as fifty-seven twelfths and one sixth is the same as two twelfths.
- 01:12
They're brothers from another mother. So what do we get when we add the numerators,
- 01:16
but keep the denominator? Fifty-nine twelfths.
- 01:19
While we aren't likely to offend anyone with our improper fraction, it's best not to take
- 01:20
any chances. Some people are so touchy. To convert it to a mixed number, we need to
- 01:22
figure out how many times twelve -- our denominator -- goes into fifty-nine.
- 01:27
The answer is four, with a remainder of eleven, which we write this way:
- 01:32
Four and eleven-twelfths. Ugh. It seems we're going to have to scour
- 01:37
the factory floor for another twelfth before we can piece this baby back together.
- 01:41
You'd better find a comfortable spot and get settled.
- 01:43
It's going to be a long night.
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