Amruta Deshpande
May 6, 2019

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Subtracting fractions with unlike denominators is not all that difficult if done in a systematic way. Here's an post on how to subtract fractions with unlike denominators.

Mathematics is about numbers and calculations. Addition and subtraction are the basic mathematical applications. But when it comes to subtracting fractions, it gets a little tougher, and that's especially if the fractions have different denominators.

Subtracting fractions with whole numbers is pretty easy! These are simple steps that will help you in subtracting fractions with unlike denominators. Have a look at them.

i.e. : 4÷5 - 2÷3

The common denominator for the two fractions will be 3×5 = 15

For the first fraction, 15 ÷ 5 = 3, hence multiply the old numerator by 3,

i.e., 4 × 3 = 12, so 12 is the new numerator for the first fraction. Similarly, find the new numerator for the second fraction, 2÷3.

15÷3 = 5, multiply 2 by 5, 2×5 = 10

So, your new fractions have the same denominators and are equivalent. They are 12÷15 and 10÷15.

i.e., 4 × 3 = 12, so 12 is the new numerator for the first fraction. Similarly, find the new numerator for the second fraction, 2÷3.

15÷3 = 5, multiply 2 by 5, 2×5 = 10

So, your new fractions have the same denominators and are equivalent. They are 12÷15 and 10÷15.

12÷15 - 10÷15 = (12 - 10)÷15 = 2÷15

Wasn't that easy! This was about subtracting fractions with different denominators and whole numbers. But do you know how to go about subtracting fractions with mixed numbers, or simply, mixed fractions? Now, that can be a little difficult. But if you get the basics right, you will have fun with these mixed fractions.

We're sure you know what mixed fractions are! Subtracting mixed fractions can be done in two different ways. You can either convert the mixed fractions into improper fractions, and then use the given method for subtracting, or you could subtract the whole numbers and fractions individually, and then combine them. Let us see the first method in detail.

3¼ is the mixed fraction, where 3 is the whole number, 4 is the denominator, and 1 is the numerator. So, 3×4 = 12+1 = 13, is your new numerator, and the 1¾ is the new fraction.

Similarly, 1⅔ can be simplified as, 1×3 = 3+2 = 5, 5÷3 is the new second fraction.

Similarly, 1⅔ can be simplified as, 1×3 = 3+2 = 5, 5÷3 is the new second fraction.

The new denominator is 3×4 = 12

39÷12 - 20÷12 = (39 - 20)÷12 = 19÷12.

So, now when you have to subtract fractions, be it whole numbers or mixed, just follow these simple steps, and you will get the numbers right.