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Welcome to 360.vn, a website for elementary and junior high school students. In this video, we will learn how to add and subtract fractions in the 4th grade math program. In the previous videos, we learned how to add and subtract fractions before doing some calculations. To add and subtract fractions, you can do it in the following steps. The first step is to add and subtract fractions. This is very important. In the previous videos, I talked about adding and subtracting fractions many times. Adding and subtracting fractions is the first step we have to do before we do the calculations on the fractions. After adding and subtracting fractions, we move on to the second step, which is to find the result fraction. The result fraction in the addition of fractions is the sum of the numbers. The result fraction is the sum of the numbers we just found in the first step. The third step is to subtract the result fraction from the subtraction fraction if necessary. I still leave these three steps. We will learn how to add and subtract fractions through the following examples. For example, 2 times 3 plus 1 times 2 is equal to how many? We do it in the following steps. The first step is to sum the fractions. We have learned a lot about this sum in the previous videos. Now I will do it quickly and you can follow along. The sum of these two fractions is 3 and 2. The total number we find is 6. So we will convert these two fractions into fractions with the number 6. For the fraction 2 times 3, we have to multiply both the number and the number. The number is multiplied by 2 to get 6 and the number is also multiplied by 2. For the fraction 1 times 2, to get the number 6, we multiply the number by 3 and the number is also multiplied by 3. So we have converted the fraction 2 times 3 into this fraction. Of course, the number is 6 and the number is 2 times 2 is 4. We get the fraction 4 times 6. Plus the fraction 1 times 2, both the number and the number multiplied by 3. We get the fraction 3 times 6. So we have just completed the first step, which is to sum the fractions. Let's move on to the second step. To find the fraction result, we just need to take the numerator plus the denominator, which is the sum of the numerators. And the denominator is the common denominator we just found, which is 6. So what is the fraction result? 4 plus 3 is the numerator and the denominator is 6. We get the fraction 7 times 6. Let's move on to the next example. 1 divided by 3 plus 1 divided by 4 is how much? These two numbers are different from each other in terms of the numerator. We also sum them. The common denominator is 12. I would also like to remind you that if you are not familiar with summing numbers, please pause this video here. Let's go back to the videos on summing numbers by clicking here. To learn more about summing numbers before doing math, let's continue. 1 divided by 3 is 3. To get the number 12, we multiply it by 4. We also multiply the numerator by 4. 1 divided by 4 is 4. To get the number 12, we multiply it by 3. We also multiply the numerator by 3. So we have converted 1 divided by 3 into this fraction. Of course, the numerator is 12, and the denominator is 1 multiplied by 4 is 4. So we get 4 divided by 12. 1 divided by 4 multiplied by the denominator is 13. So we get 3 divided by 12. Now, it is very easy to calculate the fraction result. After the fractions have the same numerator, we also multiply the numerator by the denominator. 4 multiplied by 3 is 7. The denominator is 12. So we get 7 divided by 12. Let's move on to the next example. 2 divided by 3 plus 1 divided by 6 is? These two numbers are different from each other. So we also have to convert the numerator. However, if you notice, 6 divided by 3, so we can choose the denominator as 6. So we keep 1 divided by 6. What about 2 divided by 3? We multiply the numerator by 2, and the denominator by 2. Now we will calculate the fractions after converting. 2 divided by 3 plus 1 divided by 2, so we get 4 divided by 6. We keep 1 divided by 6. We multiply the numerator by 1 divided by 6. After the numerator is 6, we just have to add the denominator. Just like adding the natural numbers, 4 plus 1 is 5, and the denominator is 6. So we get 5 divided by 6. 2 divided by 3 plus 1 divided by 6 is 5 divided by 6. The next example. 1 divided by 4 plus 5 divided by 6 is? These two numbers are different from each other. So we have to convert the numerator. You can choose the denominator as 24. We see that 24 divided by 6 is 4, and 24 divided by 4 is 6. However, there is another denominator smaller than 24. You just have to watch the videos about the numerator. You will see that the denominator of 6 and 4 is 12. From now on, we multiply the fractions. 1 divided by 4 plus the numerator. We get 12. The denominator is 3. 5 divided by 6 plus the denominator is 2. The denominator is 2. Let's calculate the values of the fractions. 1 divided by 4 plus the denominator is 3. We get 3 divided by 12. 5 divided by 6 plus the denominator is 2. We get 10 divided by 12. After we have the common denominator, which is 12, we just have to add the denominators. The common denominator is 12. We have the result. 3 plus 10 is 13. The denominator is 12. What is the most important knowledge about the denominator? For example, we have to add the numerator. We just have to add the denominator. It's like adding the natural number. It's not difficult. We have to add the denominator. It means we have the common denominator. The knowledge about the denominator is the most important knowledge. It's the first step we have to do. Let me remind you again. If you don't understand the denominator, let's go to the other knowledge. You can click here to watch the video