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  • Now that you know that fractions are special numbers written like division problems,

  • were going to learn about some different types of fractions, and where theyre located on the number line.

  • Because fractions are division problems, their value depends on the top and bottom numbers and the relationship between them.

  • There are a few basic rules about that relationship that will help us estimate the value of a fraction

  • and know about where it should be on the number line.

  • The first rule is: If the top number of a fraction is zero,

  • then the value of the fraction is always zero, no matter what the bottom number is.

  • For example, zero over two and zero over twenty-thousand are both just zero.

  • I like to call these fractions, “zero fractions” … ya knowcuz they equal zero.

  • Oh.. and by the wayyou can never have zero as the bottom number of a fraction

  • because you can’t divide something into zero parts, so don’t even try it.

  • The next rule is this: If the bottom number is bigger than the top number

  • then the value of the fraction will be greater than zero but less than one.

  • That means itll be somewhere in this section of the number line.

  • Any fractions that have values in this range are calledProper Fractions

  • because we can use these values to represent smaller parts of things.

  • Our third rule is this: If the top number and the bottom number are the same,

  • then the value of the fraction is always just one.

  • So, whether you have one over one, five over five or one-hundred over one-hundred, the value is always just one.

  • I’m going to call this kind of fraction a “whole fractionbecause its value represents one-whole.

  • Ohand in case youre wondering, this rule doesn’t apply to zero over zero,

  • because like I told you, having a zero on the bottom of a fraction is a big no-no.

  • Okay, our last rule is this:

  • If the top number is greater than the bottom number, then the value of the fraction will be bigger than one.

  • That means itll be somewhere in this section of the number line, which goes on forever.

  • These are calledImproper Fractions’, because even though theyre written like regular fractions,

  • since their value is greater than one, they aren’t really used to represent smaller parts of things.

  • Alright, these rules show that we have four main types of fractions:

  • We havezero fractions’, ‘proper fractions’, ‘whole fractions’, andimproper fractions’.

  • Knowing that these main types are in order from smallest to largest on the number line

  • allows you to do some very simple comparisons between the four types of fractions.

  • That’s because we know that a zero fraction is always less than a proper fraction,

  • and a proper fraction is always less than a whole fraction,

  • and a whole fraction is always less than an improper fraction.

  • Let’s do a few comparisons to get the hang of it

  • Here we have 1/5 and 0/8:

  • Since 1/5 is a proper fraction and 0/8 is a zero fraction,

  • 1/5 is greater than 0/8

  • Now let’s do 3/8 and 2/2:

  • 3/8 is a proper fraction and 2/2 is a whole fraction,

  • so that means that 3/8 is less than 2/2

  • Now what about 9/9 and 32/32 ?

  • Ahnow that’s easy.

  • Since they are both whole fractions, and whole fractions are always equal to one,

  • these fractions are equal.

  • And finally, what about 1/2 and 5/4 ?

  • Now we know that 1/2 is a proper fraction,

  • but 5/4 is an improper fraction because its top number is bigger that its bottom number.

  • So that means that 1/2 is less than 5/4.

  • Now that we know that there are four basic types of fractions, and weve learned where they fit on the number line,

  • let’s learn more about how the relationship between the top and bottom numbers effects the value of a fraction.

  • Let’s go on a journey down our number line.

  • Now were gonna start with thiszero fraction’ (zero over twenty)

  • and its value puts us here at zero on the number line.

  • To get moving, all we have to do is start changing the value of our fraction by increasing the top number.

  • Were going to leave the bottom number the same the whole time though.

  • Alright! Let’s go!

  • We haven’t gotten very far from zero yet,

  • and you might have noticed that the top number is still very small compared to the bottom number.

  • But, as the top number gets bigger, the value of our fraction is increasing.

  • That tells us that if a fraction’s top number is a lot smaller than its bottom number,

  • then its value is going to be close to zero. …in this part of the number line.

  • Look at thiswere almost to ten on top,

  • and since ten is half of twenty, were almost to one-half on the number line.

  • It’s pretty easy to figure out what half of something, or double of something is,

  • and we can use that to help us compare fractions.

  • like we know that 9 over 20 is going to be really close to 1/2 on our number line.

  • Alright, so weve passed one-half now, and were making our way to the number ‘1’.

  • Notice that our top number keeps increasing, and it’s getting closer and closer to twenty.

  • In fact, when it reaches 20, well have arrived at '1' because twenty over twenty is a whole fraction.

  • Knowing this can also help you estimate a fraction’s value.

  • Whenever you see a fraction with a top and bottom number that are almost the samelike 19 over 20,

  • you know that the value is close to ‘1’.

  • There, weve passed ‘1’ now, but were still going and our top number is now bigger than our bottom number,

  • which means we have an improper fraction.

  • You can see that the bigger the number gets, the bigger the value of the fraction,

  • and we could keep on going forever and ever, but that might take all day! [laughter]

  • Okay, so our journey showed us some pretty useful regions of the number line:

  • the region near zero, where the top number is much smaller than the bottom number.

  • the region near one-half, where the top number is about one-half of the bottom number.

  • the region near ‘1’, where the top number and bottom number are about the same.

  • and the region past ‘1’ where the top number is bigger than the bottom number, and it keeps on going forever.

  • Knowing about these regions can sometimes help you quickly estimate the value of some fractions.

  • For example, you can estimate that 1 over 16 is going to be pretty small. …close to zero on the number line.

  • And you can estimate that 29 over 31 is going to be almost ‘1’

  • because there is not much difference between the top and bottom numbers.

  • And if you have the fraction 14 over 30,

  • you can estimate that itll be about one-half since 14 is close to 15 and 15 is half of 30.

  • Alright, that wraps up this section,

  • and I hope it’s helped you understand the different types of fractions and where they are on the number line.

  • Youll understand even better if you do the exercises for this section.

  • Good luck and I’ll see you next time.

  • Learn more at www.mathantics.com

Now that you know that fractions are special numbers written like division problems,

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B1 中級 美國腔

數學反常學 - 分數的類型 (Math Antics - Types of Fractions)

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    Yassion Liu 發佈於 2021 年 01 月 14 日
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