To be able to reduce fractions, you must understand the concept of equivalent fractions.
Here’s an example.
If I have 6 cherries, and I give away 3 of those cherries, then I can represent this as follows:
( 111) 111
I gave away 3/6 of my cherries, but, in essence, I gave away half of my cherries. Half is the same as 1/2.
So proportionally speaking, the fractions 3/6 and 1/2 are equivalent, and at the same time, they represent different amounts.
Let’s reduce:
4/8.
To know if the fraction can be reduced, ask yourself if the bottom number can be divided by the top number without leaving a remainder.
For example, in the fraction, 3/6, we know that 6 can be divided into 3 two times.
Therefore, we go ahead and reduce it.
Say: 3 into 3 = 1
3 into 6 = 2
Reduced as: 1/3
Using the Highest Common Factor to Reduce Fractions.
Sometimes, the bottom number cannot be divided by the top number, but the fraction can still be reduced. That’s why we have to look for a “common factor” shared by the top and bottom number.
For example, in the fraction 18/20, the bottom number 20 cannot be divided by the top number 18. Nevertheless, the fraction can be reduced!
How? By dividing both the top and bottom number by 2! The number 2 can divide both numbers without leaving a remainder. Therefore, the number 2 is a factor of both number. Since the number 2 is a factor of both 18 and 20, it is called a “common factor.”
But the number 1 can also divide 18 and 20! Can’t it? Of course it can! So why don’t we use the factor 1? Obviously because it would get us nowhere! Both numbers divided by 1 would remain the same. The idea then, when reducing fractions, is to look for the HIGHEST COMMON FACTOR.
Let’s break this down a little bit.
The factors of a number are numbers which can divide that number without leaving a remainder.
For example:
Factors of 18: 1, 2, 3, 6, 9 and 18.
Factors of 20: 1, 2, 4, 5, 10 and 20.
What are the common factors of the numbers 10 and 20?
Common factors means factors which both numbers have, which are: 1 and 2 only.
What is the highest common factor of 18 and 20? The number 2 is the highest common factor of 18 and 20.
We always use the highest common factor of the top and bottom numbers, abbreviated HCF to reduce a fraction.
Note: In this article, I used the expressions “top number” and “bottom number” of a fraction. But you should remember that the correct name for the top number in a fraction is the numerator, and the bottom number is called the denominator.