TenMarks teaches you how to add fractions with unlike denominators.
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Learn about Adding Unlike Fractions In this lesson, let’s learn how we add unlike fractions. Unlike fractions means two fractions that have different denominators. These are not the same. So we are given a problem that says we have to add two fractions. One is ¾ the other is ½. As we could see, they have different denominators. Well in order to get them to add, I have to convert them or rename one of them. So it has same denominator as the other, you have to rename both at times but in this case we should be able to do denominators. So let’s take ¾, that’s got a bigger denominator called 4. Now let’s take this one, ½. What do I have to do to get this to have a denominator of 4? Well 2 can be multiplied by 2. Top can be multiplied by 2. So if I want the denominator to go from 2 to 4, I have to multiply it by 2. So we have to do the same to the top. 1×2 is 2. So ½ is the same as 2/4. So now that I have this right, what am I left with? I have to add ¾+2/4. Instead of ½ I’ll put 2/4. Well this is a little easier to do since we have the same denominator, we copy the denominator forward and we add the numerators, 3 and 2 is 5. That’s the answer. Another way to look at this problem would be to do it slightly differently. Let’s look at taking of sheet, and break it down into quarter pieces. Four equal pieces. This is ¼, this is ¼, this is ¼ and this is ¼. So we have to take ¾ which means I shade 3 parts out of 1. Now let’s take ½ if I take the same sheet. Take the same size sheet and break it up into two halves, this is one half, and this is one half. As we can see, ½ is the same as 2/4. So I can say this is the same as 2/4 because with this and with two of this parts are the same. So what do I have? If I break this down, I’ve got 2/4. So what do I have? 2/4 and 1, 2, 3, 4, 5. So I have 5/4 as the total addition which is where we ended up. So I just want to have a recap. What we do when we are adding unlike fractions is we write the fractions down but we have to convert both the fractions or rename them so that they have the same denominator. In this case ½ is a smaller fraction when it comes to smaller denominators. So I can multiply the denominator and the numerator by 2, to get the equivalent fraction which is 2/4. So now I just have to have this and this, which is easier to do. If the fractions have the same denominator, that’s carried over. And we just simply add the numerators.