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00:00Hi kids! Today, we will learn how to add and subtract with like and unlike fractions.
00:09So let's get started.
00:12First of all, let's revise what are like fractions.
00:17Fractions with same denominators are called like fractions.
00:23Now, let's see how we add and subtract like fractions.
00:29Example. Here are two fractions, 4x5 and 3x5.
00:38We have to add them.
00:41We just add the numerators of like fractions to add the fraction.
00:48Like for adding 4x5 and 3x5, we just add the numerators.
00:56Adding the numerators, that is, 4 and 3, we get 7.
01:02So, 7x5 is a sum of 4x5 and 3x5.
01:10Denominators remain the same.
01:13We just add the numerators to add the like fractions.
01:19Let's have a look at more examples.
01:23Here, we have another example.
01:26We have to add 8x9 and 6x9.
01:31These are like fractions as the denominators are same.
01:35So, we just have to add the numerators.
01:40Adding numerators, that is, adding 8 and 6, we get 14.
01:47Denominator will remain the same.
01:50So, the sum of fractions 8x9 and 6x9 is 14x9.
01:58Now, let's see how we subtract like fractions.
02:04Here, we have an example.
02:07We have to subtract 6x9 from 8x9.
02:12These are like fractions as denominators are same.
02:16Both are 9.
02:18We just have to subtract the numerators to subtract the fractions.
02:24Subtracting the numerators, that is, subtracting 6 from 9, we get 2.
02:31So, 2x9 is the difference between two fractions, 8x9 and 6x9.
02:40Here, we have another example.
02:44We have to subtract 6x4 from 9x4.
02:49These are like fractions as denominators of both the fractions are same.
02:56We just have to subtract the numerators in order to subtract the fractions.
03:02Subtracting the numerators, that is, subtracting 6 from 9, we get 3.
03:09So, our answer is 3x4.
03:133x4 is the difference between two fractions, 9x4 and 6x4.
03:21So, adding and subtracting like fractions is very simple.
03:26Now, let's learn how we do addition and subtraction on unlike fractions.
03:34Let's first learn what are unlike fractions.
03:39Fractions with different denominators are called unlike fractions.
03:44Here, we have two unlike fractions, 2x3 and 3x4.
03:51Their denominators are different, so we can't add them directly, that is, by just adding their numerators.
03:59So, let's see how we add them.
04:03For adding the unlike fractions, first we have to convert them to like fractions.
04:09That is, we have to make their denominators same.
04:13And then we add them like and like fractions.
04:18Now, we will make the denominators same using the crisscross method.
04:23Now, let's see what is the crisscross method.
04:28In this method, we multiply both the numerator and denominator with the denominator of other fractions.
04:37Like here, multiply both the numerator and denominator of 2x3 with 4.
04:45And multiply both the numerator and denominator of 3x4 with 3.
04:52So, it looks like a crisscross.
04:564 multiplied with 2, we get 8.
05:004 multiplied with 3, we get 12.
05:043 multiplied with 3, we get 9.
05:084 multiplied with 3, we get 12.
05:12So, we got 8x12 and 9x12.
05:17Now, these two fractions are same as their denominators are same.
05:24Now, we can add them like like fractions.
05:28We just have to add the numerators to add them.
05:32Adding 8 and 9, we get 17.
05:36So, 17x12 is our answer.
05:41Now, let's take another example.
05:44We have to add these two fractions.
05:486x2x3 plus 7x4.
05:53Here, one of the fraction is a mixed fraction.
05:57So, first we convert the mixed fraction to an improper fraction.
06:02We multiply the whole number with the denominator and add numerator to it.
06:09Denominator remains the same.
06:12So, multiply 6 by 3 is 18.
06:17We have converted the mixed fraction to an improper fraction.
06:22Now, we have two unlike fractions to add.
06:26We have to add 20x3 and 7x4.
06:32We learned that we need to convert unlike fraction to like fractions before we add them.
06:38That is, the denominator should be the same.
06:42Now, use a crisscross method to make them like fractions.
06:48Now, we will multiply both the numerator and denominator of 20x3 with 4.
06:56And, we will multiply both the numerator and denominator of 7x4, denominator of other fraction.
07:06So, multiply it with 3x3.
07:11So, it becomes our crisscross.
07:1520x4 equals 80.
07:193x4 equals 12.
07:23So, it becomes 80x12.
07:273x7 equals 21.
07:323x4 equals 12.
07:36So, it becomes 21x12.
07:41Now, we have two like fractions to add.
07:44And, we know adding like fractions is easy.
07:49Just add the numerators to add the fraction.
07:53And, adding 80 and 21, we get 101.
07:58So, the answer is 101x12.
08:04Now, let's learn an example where we will subtract a like fraction.
08:10First of all, we always subtract the smaller number from the bigger number.
08:15So, same as for fractions.
08:19Always subtract the smaller fraction from the bigger fraction.
08:24Now, let's subtract two unlike fractions.
08:28We have to subtract 5x9 from 2x6x7.
08:34That is, we have to subtract 5x9 from a mixed fraction.
08:41So, first we convert the mixed fraction to an improper fraction.
08:46For that, we will multiply 7x2 and then add 6 to it.
08:537x2 equals 14.
08:5814 plus 6 equals 20.
09:03Denominator remains the same, so its improper fraction is 20x7.
09:10So, we have to subtract 5x9 from 20x7.
09:15So, these are unlike fractions.
09:19So, first we use the crisscross method to convert them to like fractions.
09:25In the crisscross method, what we will do is multiply 20x7 with 9x9.
09:34That is the denominator of the other fraction.
09:38And multiply 5x9 with 7x7.
09:43That is the denominator of the other fraction.
09:4720 multiplied with 9, we get 180.
09:529 multiplied with 7, we get 63.
09:565 multiplied with 7, we get 35.
10:019 multiplied with 7, we get 63.
10:06Now we have two like fractions.
10:09And we can subtract the numerators to subtract the fraction.
10:14Subtracting 35 from 180, we get 145.
10:21So, 145 by 63 is our answer.
10:27So kids, now you know how to add or subtract like and unlike fractions.
10:34Now you may go ahead and take a quiz to learn more.
10:38Bye-bye.