跟讀練習: Multiplying Fractions - The Easy Way! - 通過影片學習英語口語

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In this video we're going to focus on multiplying fractions.
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So let's start with a simple example.
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Let's multiply 3 over 5 by 4 over 7.
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Now for each of these examples feel free to pause the video and try these problems yourself.
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See if you can get the answer.
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So what do we need to do in this problem?
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How can we multiply these two fractions?
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When multiplying fractions you need to multiply across.
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So we're going to multiply 3 and 4 together.
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3 times 4 is 12.
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Next, we need to multiply the two denominators together.
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5 times 7 is 35.
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And so that's it for this problem.
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That's all we need to do.
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And the answer is 12 over 35.
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Now, it's important to check and see if you could reduce the fraction.
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And for this example, we can't simplify the fraction.
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So the final answer is 12 over 35.
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Now let's try another example.
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Go ahead and multiply these two fractions.
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2 over 5 times 3 over 11.
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So once again, we're going to multiply across.
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2 times 3 is 6.
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And then we're going to multiply 5 and 11.
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5 times 11 is 55.
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And so this is the answer.
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We can't simplify this answer.
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Now let's try some examples where we have to simplify the final answer.
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So let's multiply 3 over 2 by 4 over 9.
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Go ahead and try this.
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3 times 4 is 12.
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And 2 times 9 is 18.
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So we get 12 over 18.
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How can we reduce that fraction?
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Now, both of these numbers are even, so we can divide 12 and 18 by 2.
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12 divided by 2 is 6.
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18 divided by 2 is 9.
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Now, can we reduce this fraction, or is that the final answer?
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6 and 9 are both divisible by 3, so we could divide both numbers by 3.
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6 divided by 3 is 2, 9 divided by 3 is 3.
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So our final answer is 2 over 3.
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Now there's another way in which you can get the same answer.
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So once you got to, let's say this part, you could do it this way.
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You could say 12 is 6 times 2, and 18 is 6 times 3.
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So at this point, you can cancel the 6, and this will give you the final answer of 2 over 3.
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So that's another way in which you could reduce a fraction.
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Now let's work on another example that's similar to the last one.
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4 over 3 times 9 over 8.
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So pause the video and work on this example.
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So let's multiply across.
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What is 4 times 9?
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4 times 9 is 36.
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And what's 3 times 8?
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3 times 8 is going to be 24.
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So how can we reduce 36 over 24?
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24 and 36 are multiples of 12.
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12 times 3 is 36, and 12 times 2 is 24.
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So it really helps to know your multiplication tables.
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So at this point, we can cancel our 12.
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And so the final answer is going to be 3 over 2.
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Now let's talk about what to do when multiplying two fractions
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that contain large numbers such as this one now what I
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don't recommend is multiplying across 24 times 45 it's gonna be a big number let's see what
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that number is gonna be if you multiply across that's gonna give you a thousand
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and eighty and then if you multiply 27 by 32 that's gonna give you a large number as well.
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That's going to be 864.
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So what are you going to do to reduce this fraction?
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That's not going to be fun and it's going to take a long time.
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So there has to be an easier way of getting the answer for this problem.
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And the key is to simplify before you multiply.
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So, for instance, 28, we can write that as 8 times 3.
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27, we can write it as 9 times 3, because 9 times 3 is 27.
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Now, 45, you want to break it down into a number with a 9, so you can cancel this 9.
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It turns out that 9 times 5 is 45.
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And 32, we can represent it as 8 times 4.
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So you want to break down these large numbers into smaller numbers in such a way
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that you can cancel some of those smaller numbers.
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So we can cancel an 8, we can cancel a 9, and we can cancel a 3.
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And our final answer is just going to be 5 over 4.
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we don't have to simplify any further than this as you
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can see this second method is a lot easier than the first so
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if you have large numbers I would avoid multiplying them to get even bigger numbers instead simplify before you multiply
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so now it's your turn try this 56 over 44 times 55 over 40
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go ahead and multiply these two fractions.
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So let's not multiply 56 by 55.
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Let's avoid that.
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56, we can write that as 8 times 7.
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44 is 11 times 4.
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And 55 is 11 times 5.
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40 is 8 times 5.
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So we can cancel an 8.
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We can cancel an 11.
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And we can cancel a 5.
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So the final answer is 7 over 4, and that's it.
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Now, what if you get a problem that looks like this?
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What is 8 multiplied by 5 over 3?
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How can you take a whole number and multiply it by a fraction?
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The key is to convert the whole number into a fraction.
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8 is the same as 8 over 1.
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In this case, 8 and 5, they're not large numbers, so we can multiply across.
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And we can't really simplify before we multiply in this case.
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So 8 times 5, that's going to be 40.
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And then if we multiply 1 and 3, it's going to give us 3.
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So our answer is 40 over 3 as an improper fraction.
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Try this one.
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7 over 6 multiplied by 9.
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Go ahead and work on that example.
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So let's rewrite 9 as 9 over 1.
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Now this one we could simplify before we multiply if we want to.
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6, we can write that as 3 times 2.
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And 9 is 3 times 3.
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So we can cancel a 3.
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And so we're left with 7 times 3, which is 21 and 2 times 1 which is 2.
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So the answer is 21 over 2.
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By the way, if you want more videos on fractions, feel free to check out my next video on dividing fractions.
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Which I'm going to post a link to that video in the description section of this video that you're currently watching.
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But now let's get back to our next problem.
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So let's say if we have 12 over 28 times 18 over 30 times 35 over 27.
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How can we multiply these three fractions?
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So go ahead and try this problem.
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12 we can write
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that as 6 times 2 28 we could say it's 7 times 4 18 we can write
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that as 6 times 3
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but yeah i'm gonna make that 9 times 2 because there's 27 and 27 is divisible by 9
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30 is 6 times 5, 35 is 7 times 5, and 27 is 9 times 3.
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So we can cancel a 9, we can cancel a 7,
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we can cancel a 5, we can cancel a 6,
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and notice that we can also cancel 4.
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2 times 2 is 4.
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So these 2s can cancel the 4 on the bottom.
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So what's our final answer here?
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Notice that every number in the numerators of the 3 fractions have been cancelled.
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So what numbers should we put on top then if there's nothing to write?
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Well, if we think about this, 9 divided by 9.
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The reason why that cancels is because 9 over 9 is 1.
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7 divided by 7 is 1 So when everything cancels, the number to right is a 1 Now we do have a 3 on the bottom,
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so our final answer for this problem is 1 over 3 So this is the solution

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本課的詞彙與口語要點

這節 B1 級別的口語課以影片“Multiplying Fractions - The Easy Way!”為素材。 影片中反覆出現的詞有:multiply, fraction, cancel, answer, simplify。 這段影片共有 137 個句子、1137 個單詞可供跟讀。 講話部分時長為 10:15。 說話人語速平穩,每分鐘約 111 個詞,很適合跟讀。 89% 的單詞屬於英語最常用的 3,000 詞,詞彙容易理解。

影片中的重點詞彙

影片中最難的 10 個單詞,附發音和釋義:

單詞發音釋義
multiply 動詞/ˈmʌltɪplaɪ/增長 /增長
cancel 動詞/ˈkæn.sl̩/劃, 勾
fraction 名詞/ˈfɹæk.ʃən/部分
divide 動詞/dɪˈvaɪd/分, 分裂
simplify 動詞/ˈsɪmplɪfaɪ/簡化 /簡化
pause 名詞/pɔːz/停頓 /停頓, 暫停 /暫停
denominator 名詞/dɪˈnɒmɪneɪtə(ɹ)/分母
multiplication 名詞/ˌmʌltɪplɪˈkeɪʃən/乘法
numerator 名詞/ˈnuː.məɹˌeɪ̯.təɹ/分子
rewrite 動詞/ɹiˈɹaɪt/重寫 /重寫

影片中出現的短語動詞

單詞發音釋義
go ahead 動詞/ˌɡoʊ əˈhɛd/請便 /請便
break down 動詞壞了 /壞了, 出故障
check out 動詞退房
turn out 動詞原來 /原來

值得反覆跟讀的句子

影片中簡短而完整的句子,可以直接用在日常對話裡:

  • How can we multiply these two fractions?
  • That's all we need to do.
  • We can't simplify this answer.
  • How can we reduce that fraction?
  • How can we multiply these three fractions?

影片中的語法

說話人最常用的結構,並附上影片中的原話:

結構影片中的用法
比較級 -er than / more … than — 比較兩個事物further than · easier than
“going to” 表將來 be going to + 動詞 — 計劃或明顯即將發生的事we're going to focus · we're going to multiply · is going to be
義務:must / have to / need to 表示某事是必要的need to multiply · have to simplify · has to be

需要注意的發音

說話人用了 19 次縮略和弱讀形式,例如 gonna, we're, can't。請按聽到的簡短形式來說。

  • “sh” 和 “zh” 音: fraction /ˈfɹæk.ʃən/, multiplication /ˌmʌltɪplɪˈkeɪʃən/
  • 長單詞——注意重音位置: divisible [dɪˈvɪzɪbəɫ], denominator /dɪˈnɒmɪneɪtə(ɹ)/, multiplication /ˌmʌltɪplɪˈkeɪʃən/, numerator /ˈnuː.məɹˌeɪ̯.təɹ/

中文母語者容易讀錯的音:

  • /v/ — 不要讀成 /w/,上齒輕觸下唇: divide /dɪˈvaɪd/, divisible [dɪˈvɪzɪbəɫ], convert /kənˈvɝt/
  • 詞尾子音 — 要讀清楚,後面不要加母音: divide /dɪˈvaɪd/, pause /pɔːz/, rewrite /ɹiˈɹaɪt/, convert /kənˈvɝt/
  • /æ/ — 嘴張大,不要讀成 /e/: cancel /ˈkæn.sl̩/, fraction /ˈfɹæk.ʃən/

如何用這段影片練習

  1. 先完整聽一遍影片,不要開口,記下不認識的單詞。
  2. 用正常速度逐句跟讀,每句重複到你的節奏與說話人一致為止。
  3. 錄下自己的聲音並與原聲對比,特別注意 multiply, cancel, fraction 這類單詞。

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