A ratio is a mathematical means of comparing one value to another. You hear the term "ratio" used in relation to studies or analyses of various sets of data, such as in demographics or the performance ratings of products. Proportions and fractions are intertwined with ratios. Both proportions and fractions deal with the comparison of multiple values. You can use proportions and fractions as alternative means of writing ratios. You may have to perform this type of task in a middle school, high school or college math course.

Write a ratio in sentence form. For example, if you have one red button and two blue buttons, the ratio of red to blue buttons can be stated as "1 to 2."

Write the ratio in its simplest form. Do this by dividing both numbers by the largest number that will divide into both evenly. This is known as the greatest common factor. For example, if you have 10 red buttons and 20 blue buttons, you can divide both numbers by 10 to get a ratio of 1 to 2.

Write a ratio by adding a colon between the two numbers. In the example using buttons, you could write the ratio of 1 to 2 as 1:2.

Rewrite a ratio as a fraction. The first number will be the numerator, and the second number will be the denominator. In this example, you would change the ratio of 1 to 2 to the fraction 1/2.

Compare ratios using a proportion, which consists of two equal ratios separated by an equal sign. For instance, if you are comparing the ratios 1/2 and 10/20, you could write 1/2 = 10/20.