Equivalent fractions and Simplest form, Grade 4, Chapter 9 page 162

追加: 2026-05-12

[00:00:00]In this video, we're going to talk about equivalent fractions.

[00:00:04]For equivalent fractions, we can for finding equivalent fraction, we can use two operations, multiplication and division.

[00:00:13]>> [snorts] >> But in this video, we only going to use multiplication. Now, for example, we have 1/4.

[00:00:19]In order to find an equivalent fraction for 1/4, we will multiply 1/4. But for example, we're going to multiply it by two.

[00:00:30]Always try to multiply it by an easy number first.

[00:00:34]But whatever we do to the numerator, we multiply the numerator by two, we will do the same to the denominator. So, we also multiply the denominator by two.

[00:00:45]Now, we just multiply. 1 * 2 will be 2.

[00:00:51]And 4 * 2 will be 8.

[00:00:53]So, 2/8 is an equivalent fraction of 1/4.

[00:01:01]Another example.

[00:01:03]For example, we have 4/6. Same thing. We will multiply it by two.

[00:01:09]Both of them, the numerator and denominator. Don't forget, we don't do it one of them alone. We should do We should multiply both of them.

[00:01:17]Now, 4 * 2 will be 8.

[00:01:20]>> [snorts] >> 6 * 2 will be 12. So, 8/12 is another equivalent fraction for 4/6.

[00:01:28]We have a question.

[00:01:31]In this question says, "Write two equivalent." This is our keyword. Two equivalent fraction for each.

[00:01:40]For example, the first time we have 2/4.

[00:01:43]Same, remember? For finding the first equivalent fraction, we multiply it by two.

[00:01:50]Then it will be 4/8.

[00:01:54]But we are not done because the question says two equivalent fraction and we only found one.

[00:02:00]So we will write the fraction again.

[00:02:06]2 over 4 and this time we will multiply it by a different number.

[00:02:11]We cannot multiply it by one because the fraction will stay the same. We want it to be different in in number forms. So we multiply it by three.

[00:02:25]Now it will be 2 * 3 will be 6.

[00:02:31]4 * 3 will be 12. So we found two equivalent fractions.

[00:02:36]This is the first one.

[00:02:39]And this is the second one. For which fraction? For 2 over 4.

[00:02:44]Another example.

[00:02:47]7 over 9. Same we multiply it by two first. Multiply it by two.

[00:02:53]It will be 14 over 18.

[00:02:57]This is first.

[00:03:01]For finding the second one, we will write the fraction again. 7 over 9.

[00:03:07]And this time we will multiply it by three. So it will be 7 * 3 and 9 * 3 which will be 21 over 27.

[00:03:21]And this is the second equivalent fraction.

[00:03:24]Okay. I want you to try to do that one yourself.

[00:03:28]Write two equivalent fraction for 5 over 8.

[00:03:32]I'm going to start solving in two one.

[00:03:36]>> [snorts] >> Now.

[00:03:38]First we multiply it by two. Multiply it by two.

[00:03:42]Which will be 10 over 16. This is the first one.

[00:03:48]Then for the second one, we will write the fraction again.

[00:03:52]5/8 And this time we will multiply it by three.

[00:04:00]Which will be 15. 8 * 3 will be 24.

[00:04:07]Okay. Now, in equivalent fractions, we have something else. We have simplest form.

[00:04:16]>> [snorts] >> Now, what's simplest form? Simplest form is also an equivalent fraction, finding an equivalent fraction, but in simplest form we only use division.

[00:04:29]Not multiplication, only division.

[00:04:33]Now, in order to make to find the simplest form, first we should know what's simplest form. Simplest form is another fraction that's equivalent to that, but in the smallest form. Means it cannot be any smaller.

[00:04:51]For example, we have 4/6.

[00:04:55]We said for simplest form we use division.

[00:04:58]Now, in order to know what number can I divide them to, I'm going to think about the divisibility rule first and the factors of the numbers. But in here, divisibility rules will apply because both of them are even. Four is even and six is even also.

[00:05:17]We can divide them by two because both of them are divisible by two.

[00:05:22]Now, when we divide it, 4 [snorts] / 2 will be 2.

[00:05:26]6 / 2 will be 3.

[00:05:29]I'm still thinking, can I divide them by any other number beside one and zero? Because we cannot divide them by zero. And for one, when we divide it by one, like that, the fraction will stay the same. and we said simplest form should make the the fraction smaller. So, we don't divide it by one. Now, I'll think, do I have any other number that I can divide two and three both of them together by?

[00:06:01]For example, can I divide them by two?

[00:06:03]I can divide two by two, but I cannot divide three by two.

[00:06:07]Can I divide them by three?

[00:06:09]I can divide three by three, but I cannot divide two by three. So, when we don't have any more division, we say this fraction is in the simplest form.

[00:06:21]Okay, another one.

[00:06:23]We have 14 over 21.

[00:06:26]In that one, same thing. We use division.

[00:06:32]But, now I'll think, can I divide them by two? Remember, the divisibility rule for two was the last digit should be even.

[00:06:42]Four is even, but one is not even, so I cannot divide them by two.

[00:06:47]Then I'll check the other one. Can I divide them by three?

[00:06:52]We don't have We have a multiplication that's of 21. For example, 3 * 7 is 21, but we don't have any multiplication of three that's equal to 14. 3 * 4 is 12. 3 * 5 is 15. So, we cannot divide them by three.

[00:07:10]Then we check four.

[00:07:11]Do I have any multiplication of four that's equal to 14 and 21? We don't.

[00:07:18]Then we check five. Do I have any multiplication of five that's equal to 14 and 21? We don't.

[00:07:25]Then we check six. Same thing. We don't have any multiplication of six that's equal to 14 and 21.

[00:07:32]And the last, we check seven. Do I have any multiplication of seven that's equal to 14? Yes.

[00:07:40]7 * 2.

[00:07:41]Then, do I have any multiplication of 7 that's equal to 21?

[00:07:46]Yes, 7 * 3. So, I'm going to divide them by 7.

[00:07:53]Now, it will be 14 / 7, which is 2. 21 / 7, which is 3.

[00:08:01]>> [snorts] >> And we already know 2/3 is in the simplest form.

[00:08:08]Okay.

[00:08:10]We have that question that says, "Write each fraction in simplest form."

[00:08:15]Same thing. I have 9/12.

[00:08:19]I will check.

[00:08:20]Do I have any numbers that I can divide them to?

[00:08:26]We can do that, or we can find it by the factors. What are factors? Factors are the numbers that we multiply to get to each number. For example, I'm only going to write the factors of the smaller the numerator, the smaller number. Okay? So, I'm going to write 9.

[00:08:45]And the factors of 9 are 1, 3, and 9.

[00:08:51]Then, [snorts] I'll check each one of them.

[00:08:55]We don't check one. Remember, we don't divide it by one.

[00:08:59]I will check 9. Can I divide them by 9?

[00:09:02]9 / 9? Yes, we can. But, can I divide 12 by 9?

[00:09:07]No, we cannot. Then, I'll check the other one. I have 3. Can I divide 9 by 3? Yes, because 9 3 is a factor of 9.

[00:09:16]Then, can I divide 12 by 3?

[00:09:19]Yes, we can, because 3 * 4 is equal to 12. So, we divide them by 3.

[00:09:29]Now, it will be 9 / 3 will be 3. 12 / 3 will be 4.

[00:09:36]Then, I'll check again.

[00:09:38]Can I divide them by any number? Three and four. I cannot divide them by two because three is not divisible by two.

[00:09:46]And I cannot divide them by three because four is not divisible by three.

[00:09:52]And also we cannot divide them by four.

[00:09:55]We will stop right here and say this is in the simplest form.

[00:10:00]Same for that one.

[00:10:01]6/18, same. I want you to write the factors of the numerator, which is one, two, three, and six.

[00:10:12]>> [snorts] >> Okay. Now, I want you to go to the greatest factor, which is the six.

[00:10:19]We always check the greatest factor first. Six. Can I divide six by six?

[00:10:25]Yes, because it's a factor of six.

[00:10:27]Then can I divide 18 by six? Yes, we can.

[00:10:32]Because 6 * 3 is 18. So, we divide them by six.

[00:10:40]Now, 6 / 6 will be one.

[00:10:43]18 / 6 will be three.

[00:10:45]And a note.

[00:10:48]Whenever you see the numerator one, this fraction is already in the simplest form. We cannot simplify it anymore.

[00:10:56]Because one, we cannot divide one by any number except one. And we said we don't divide it by one.

[00:11:04]Okay.

[00:11:05]I want you to pause the video and do this example yourself. I'm going to start solving in three, two, one.

[00:11:16]Now, 12/32, we can do it directly by knowing that both of them are even.

[00:11:25]We can do that or we can write the factors of 12, the numerator, which is one, then two, then three, then four, six, and 12.

[00:11:39]Then we check the greatest factor, which is 12.

[00:11:43]Do I have any multiplication of 12 that's equal to 32? We don't. That's why we cannot divide it by 12. Do I have any multiplication of six that's equal to 32? Remember, we don't check the numerator. Why? Because those [snorts] are the factors of the numerator. We divide the 12 by any of them.

[00:12:04]So, do I have any multiplication of six that's equal to 32? We don't. Then I'll check this four. Do I have any multiplication of four that's equal to 32? Yes, we do.

[00:12:16]4 * 8. That's why we will divide both of them by four.

[00:12:23]Now it will be 12 / 4 will be 3.

[00:12:29]32 / 4 will be 8. And 3/8 is in the simplest form.

[00:12:38]Okay, last example. Same. Try to do it yourself. I'm going to solve it in three, two, [snorts] one.

[00:12:47]Okay, first we write the factors of the nine, the numerator, the smaller number, which is one, three, and nine.

[00:12:57]Then we check the greatest factor, nine. Can I divide 27 by nine?

[00:13:03]Or do I have any multiplication of nine that's equal to 27? Yes, we do. 9 * 3.

[00:13:10]So, we divide them, the numerator and denominator, both of them by nine.

[00:13:16]Now it will be 9 / 9 1. 27 / 9 will be 3.

[00:13:23]And remember, whenever you see one in the numerator, this fraction is already in the simplest form.