How to Find a Fraction of a Number

by Allan Robinson

A fraction is a common method of expressing rational numbers that aren't whole numbers (integers). A fraction may also be used to determine the partial value of a rational number. The concept of fractions is generally taught at the grade school level and must be mastered before advancing in mathematics.

Identify the components of a fraction. A fraction is defined as the expression a/b, where a and b are integers. In the fraction a/b, a is the numerator and b is the denominator.

Find the fraction of an integer. You can calculate the fraction of a whole number by multiplying the number by the numerator and dividing that product by the denominator. Thus, the fraction a/b of a whole number x is given by ax/b.

Calculate the fractions of an integer for specific cases. For example, ¾ of 21 is (3x21)/4 or 63/4. This fraction is known as an improper fraction because the numerator is greater than the denominator.

Convert an improper fraction to a mixed number. A mixed number is a number that contains an integer and a proper fraction. The integer portion of an improper fraction is the largest integer less than or equal to the improper fraction. The difference between the mixed number and integer will be a proper fraction. For example, 63/4 is equal to 15.75 so the integer portion is 15 and the fractional portion is .75 or 3/4. Therefore, 63/4 = 15 3/4.

Reduce a fraction by dividing the numerator and denominator by their greatest common factor (GCF). The GCF of two integers a and b is the largest integer such that a/c and b/c are both integers. For example, the GCF of 20 and 24 is 4. Therefore, the fraction 20/24 is equal to (20/4)/(24/4) or 5/6.

Things You Will Need

  • Calculator


About the Author

Allan Robinson has written numerous articles for various health and fitness sites. Robinson also has 15 years of experience as a software engineer and has extensive accreditation in software engineering. He holds a bachelor's degree with majors in biology and mathematics.