• 0:00 - 0:06
Let's add four elevenths to nine over thirteen
• 0:06 - 0:10
In order to add these two fractions we need to find a common denominator
• 0:10 - 0:14
And that common denominator used to be the least common multiple of eleven and thirteen
• 0:14 - 0:18
And these two numbers don't share any common factors
• 0:18 - 0:22
So their least common multiple is really just going to be the product of eleven and thirteen
• 0:22 - 0:27
So we could say thirteen times eleven
• 0:27 - 0:29
Thirteen times one is thirteen
• 0:29 - 0:32
Thirteen times another one is thirteen
• 0:32 - 0:35
Or you could say thirteen times ten is a hundred and thirty
• 0:35 - 0:39
And we get: three, four, one - one hundred and forty-three
• 0:39 - 0:42
So that's going to be our common denominator
• 0:42 - 0:43
So I'll write it over here:
• 0:43 - 0:46
Something over one hundred and forty-three plus
• 0:46 - 0:49
Something else over one hundred and forty-three
• 0:49 - 0:52
And to go from four elevenths to something over one forty-three
• 0:52 - 0:55
We multiply the eleven times thirteen
• 0:55 - 0:58
--Or we multiply the denominator times thirteen--
• 0:58 - 1:01
So we're going to have to multiply the numerator times thirteen as well
• 1:01 - 1:05
And four times thirteen--let's see: four times ten is forty
• 1:05 - 1:08
Four times three is twelve, so it gives us fifty-two
• 1:08 - 1:10
And you can work that out by hand if you like
• 1:10 - 1:12
Four times thirteen is fifty-two
• 1:12 - 1:18
And then to go from thirteen to one forty-three we multiply by eleven
• 1:18 - 1:20
So if we multiply the denominator by eleven
• 1:20 - 1:22
(if we don't want to change the value of the fraction)
• 1:22 - 1:25
We have to multiply the numerator by eleven
• 1:25 - 1:27
Nine times eleven is ninety-nine
• 1:27 - 1:34
And now we're ready to add: this is equal to--our common denominator is one hundred and forty-three
• 1:34 - 1:36
And fifty-two plus ninety-nine
• 1:36 - 1:38
--Fifty-two plus a hundred would be one hundred and fifty two
• 1:38 - 1:40
And this is going to be one less than that
• 1:40 - 1:43
So it's going to be one hundred and fifty-one
• 1:43 - 1:46
And I think that's about as simplified as we can get
• 1:46 - 1:52
As far as I know, it doesn't look like there are any common factors between one fifty-one and one forty-three
• 1:52 - 1:55
So we just get one fifty-one over one forty-three
• 1:55 - 1:57
--We can write this as a mixed number
• 1:57 - 2:02
Because one forty-three goes into one fifty-one one time
• 2:02 - 2:04
One times one forty-three is one forty-three
• 2:04 - 2:08
When you subtract--let's see, this can become an eleven
• 2:08 - 2:09
This is a four
• 2:09 - 2:10
Eleven minus three is eight
• 2:10 - 2:12
You have a remainder of eight
• 2:12 - 2:21
So one fifty-one over one forty-three is the same thing as one and eight one forty-thirds
• 2:21 - 2:25
And now it becomes even more clear that these can't be simplified anymore
• 2:25 - 2:33
And we are done--this is the same thing as one and eight one forty-thirds
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Video Language:
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Duration:
02:33

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