In fractions for kids 1, we learnt about the different components of a fraction and how to convert mixed numbers into improper fractions. In this article, we will learn how to add, subtract, multiply and divide fractions and mixed numbers.
Fractions for kids 2 – Addition and subtraction
Adding or subtracting fractions can be very simple. There is one golden rule that we must all bear in mind whenever we want to add or subtract fractions. The rule is:
Before we add or subtract any 2 fractions, we must make sure that they have the same denominator.
To recap, denominator is the lower number and numerator is the upper number in a fraction.
Once both fractions have the same denominator, adding them up is as easy as adding the numerators while keeping the denominators the same. For example, if we were to solve 1/5 + 2/5, the answer would be (1+2)/5 = 3/5.
The same rule applies for subtraction of fractions. So long we have the same common denominator, subtracting fractions is just subtracting the numerators while keeping the denominator the same. For example, if we were to solve 2/5 - 1/5, the answer would be (2-1)/5 = 1/5.
Fractions for kids 2 – Finding the common denominator
We have seen how easy it is to add or subtract fractions when they have the same denominator. But how do we add or subtract if the fractions do not have the same denominator? What we can do is to change the fractions so that both have the same denominator.
For example, if we were to add ½ and ¼, we can’t add them up directly as they do not share the same denominator. In this case, we would need to change them so they have the same denominators. Recall in fractions for kids 1, we can change a fraction such as 2/4 into its simplest form which is ½. Conversely, we can also change ½ into 2/4.
To solve ½ + ¼, we simply change the fraction ½ into 2/4 and the problem becomes 2/4 + ¼ = ¾
You can do the same thing for subtraction. To solve ½ - 1/4 , just change ½ into 2/4 and we will get 2/4 - ¼ = ¼
Fractions for kids 2 – Quick way to find common denominator
Somtimes, the common denominator is not obvious. For example, to solve 1/3 + 1/5, we will need to find a common denominator for both of the fractions. One way to quickly identify the common denominator would be to multiply each fraction by the denominator of the other fraction.
Fractions for kids 2 – adding and subtracting mixed numbers
There are two ways to add or subtract mixed numbers. The first way is to add the mixed fractions directly. For example, to solve 1¼ + 2¼; we add the whole number and the fractions parts of the mixed number separately. In this case, we will add 1 and 2 together to obtain 3 and ¼ and ¼ together to obtain 2/4 or ½. The answer will then be 3½.
The second method is to convert the mixed fractions into improper fractions before adding them together (to recap on improper fraction, read fractions for kids 1). Using the above example, if we were to solve 1¼ + 2¼, we would convert 1¼ into 5/4 and 2¼ into 9/4. Now both fractions have the same denominator and we can add them up, giving an answer of 14/4. 14/4 can then be changed back into the mixed number is 3½.
Fractions for kids 2 – Multiplying fractions
Multiplying fractions is very simple; there is no need for fractions to have common denominator before we multiply or divide them. To multiply 2 fractions, we simply multiply the numerators of both fractions first, then multiply the denominators of both fractions. For example, to solve ½ x ¼, we multiply both numerators which would give us 1 x 1 = 1 followed by both denominators which would give us 2 x 4 = 8. The answer for ½ x ¼ = 1/8
Fractions for kids 2 – Dividing fractions
Dividing fractions requires an one more step than multiplying fractions. To divide fractions, we change them into a multiplication first. To do this, we switch the numerator and denominator of the fraction on the right side of the divide sign. For example, to solve ½ ÷ ¼, we change it into a multiplication by swapping the denominator of ¼ . In this case, it would become ½ x 4/1 =4/2 = 2.
Fractions for kids 2 – Multiplying and dividing fixed numbers
Unlike addition and subtraction of mixed numbers, we cannot multiply or divide mixed numbers directly. Before we multiply or divide a mixed number, we must also change the mixed number into an improper fraction.
After the mixed number is changed into an improper fraction, the multiplication or division can be carried out using the same methods mentioned above.
Fractions for kids 2 – Summary
We have learnt a couple of things about fractions today.
- We have learnt about the golden rule of having the same common denominator before adding or subtracting fractions.
- We have also learnt how to quickly find the common denominator
- We have learnt how to add and subtract mixed numbers
- Lastly, we have learnt how to multiply and divide fractions and mixed numbers
Learn about fractions by cutting up pizzas
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