Whole numbers are non-negative numbers that haven't been broken into smaller parts. For instance, the numbers two and five are whole numbers. Fractions express division from a whole number into smaller parts that may or may not themselves be whole numbers. For instance, the fraction 4/2 represents the division of the whole number four into two parts, each of which is equal to the whole number two. The fraction 4/3, however, represents the division of the whole number 4 into three parts, of which each is equal to the non-whole number 1.33.
Write the Whole Number as a Fraction Over One
Divide the whole number by one to turn it into a temporary fraction. So if you wanted to turn the whole number four into a fraction, you would start by turning it into the fraction 4/1.
Choose A New Denominator
Choose a fraction size to convert the whole number into. For instance, if you wanted to turn the whole number four (which you expressed as 4/1 in Step 1) into halves, you would choose the number two. To turn it into quarters, you would choose four, and so on.
Multiply Both Numerator and Denominator
Multiply both the numerator and denominator by the value you chose in step 2. So to turn the whole number 4 into halves, you would multiply 4/1 by 2/2 and reach a value of 8/2. This completes the conversion of the whole number four into a fraction.
TL;DR (Too Long; Didn't Read)
Here are a few additional examples:
Convert the whole number 4 into a fraction using 4 as the denominator:
4/1 × 4/4 = 16/4
Convert the whole number 6 into a fraction using 3 as the denominator:
6/1 × 3/3 = 18/3