moomoomath logo header
lime green horizontal line
Welcome to MooMooMath
study skills A teachers secret guide to your best grades
Master the 7 pillars of school success

Improve your grades and lower your stress
A-Z Video List

Reducing fractions | Factor Tree |

Step 1. Set up a factor tree for your numerator and your denominator
Step 2. Underline the prime numbers on both factor trees
Step 3. Make a list of the prime numbers for your numerator and your denominator and cross out common factors
Step 4. Multiply any remaining factors. In this example you multiply 2 * 2 = 4

factor tree 144 and 108

How to reduce a fraction using a factor tree

Many times after adding fractions,multiplying fractions, or dividing fractions, you are left with a fraction that needs to be simplified or reduced. This method involves using a factor tree in order to reduce the fraction. 
Here are the steps for reducing or simplying a fraction using a factor tree.

Step 1. Make a factor tree for the top number ( numerator) and the bottom number ( denominator).

Step 2. Underline prime numbers on your factor tree.

Step 3. Make a list of the prime numbers for your numerator and denominator.

Step 4. Cancel common factors

Step 5. Multiply the remaining factors.

Let's look at an example from the video:

Reduce or simplify     108

Reducing Improper Fractions

Definition of an Improper Fraction: A fraction that has a numerator larger or equal to the denominator is called an improper fraction.

You can also think of an improper fraction as a fraction with a value greater than one.

You reduce an improper fraction the same way you reduce a proper fraction

For example:  144

Make a list of the prime numbers for your numerator and denominators
Cross out common factors

Multiply remaining factors
You can also convert an improper fraction to a mixed number.

Step 1.  Divide the numerator by the denominator. 

Step 2. When you divide the numerator by the denominator you will get a whole number. Write down the whole number. 

Step 3. Write any remainder over the denominator.

Convert 20/6 to a mixed number.

Step 1. 20 ÷ 6 = 3 with a remainder of 2 

Step 2. Write down the whole number = 3

Step 3. Write the remainder of 2 over the denominator 2/6
               Mixed number = 3 2/6