Multiplying fractions is easy
Multiplying fractions is an impressively easy topic!
In this article, you will learn in no time how to solve any fraction multiplication exercise.
Shall we start?
The method to solve fraction multiplications is - numerator by numerator and denominator by denominator.
Let's remember this method as this is how we will proceed in all the fraction multiplication exercises.
Important observations:
- The commutative property works - as it is a multiplication exercise, the commutative property acts the same way with fractions, and if we change the order of the parts of the exercise, the result will not be altered.
- If we come across the multiplication of a fraction by a whole number or by a mixed number, we will first convert that number to a fraction.
Let's start solving and, little by little, we will see all the possibilities along the way.
Multiplication of Fraction by Fraction
Fraction by fraction multiplication exercises are very simple and are solved by multiplying numerator by numerator and denominator by denominator.
For example
32×53=156
Solution:
We multiply the numerator 3 by the numerator 2 and obtained 6 in the numerator.
We multiply the denominator 5 by the denominator 3 and obtained 15 in the denominator.
We can simplify and arrive at 52
Another exercise
21×92×31
Solution:
We will multiply the numerator by the numerator by the numerator -> 1×2×1=2
and the denominator by the denominator by the denominator 2×9×3=54
We will obtain
542
We can simplify and get to 271
Observe - Since this is a multiplication exercise we can apply the commutative property and change the order of the fractions writing them, for example, in the following way - >21×31×92, the result will not vary.
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Multiplication of an Integer by a Fraction
When we have an exercise with an integer that is multiplied by a fractional number, we will convert the integer to a fraction and then proceed to solve according to the method of numerator by numerator and denominator by denominator.
How do you convert an integer to a fraction? It's very easy!
You can convert any number to a fraction in the following way: write the given number in the numerator
and in the denominator write 1.
For example
2=12
7=17
Now let's practice this:
3×62=
Solution:
First, let's convert the whole number to a fraction:
31=3
Now let's write the exercise only with fractions:
62×13=
Let's solve using the method we learned - Numerator by numerator and denominator by denominator, we will get: 66 that is, 1.
Fraction by mixed number
We will solve multiplication exercises of fractions by mixed numbers like this:
We will convert the mixed number to a fraction.
Now we can solve using the method of numerator by numerator and denominator by denominator.
What is a mixed number?
A mixed number is, in fact, a fraction composed of a whole number and a fraction, like, for example 354.
How do you convert a mixed number to a fraction?
Multiply the whole number by the denominator.
Then add the numerator, and this will be the number that will be written in the place of the numerator.
For example
Convert the mixed number 432 to a fraction.
Solution: We will multiply the whole number by the denominator and add the numerator
4×3+2=
12+2=14
The obtained number (14) will be written in the numerator, while the denominator will not change.
This gives us:
432=314
Now let's practice multiplying a mixed number by a fraction:
43×292=
Solution:
First, we will convert the mixed number to a fraction:
We will do it the way we learned 2×9+2=20
We will write the result in the numerator and the denominator will remain the same. We obtain: 209
Let's rewrite the exercise:
43×920=
Multiply numerator by numerator and denominator by denominator, we will obtain:
3660=35
Do you know what the answer is?
Multiplication of an Integer by a Mixed Number
To solve exercises of multiplying an integer by a mixed number, we will convert both numbers to simple fractions, then proceed according to the method of numerator by numerator and denominator by denominator.
Example
5×132
Let's convert the whole number 5 to a fraction -> 15
Let's convert the mixed number 312 to a fraction -> 35
Let's rewrite the exercise and solve by multiplying numerator by numerator and denominator by denominator:
15×35=325