A ratio describes a relationship between two similar points of data. For example, such a mathematical figure may describe the relationship between a certain number of people who attended a particular school in one year. It could also describe the difference between the length and width of a television screen (called the aspect ratio). You can find ratios on a calculator in just a few seconds.

Identify the two numbers in your ratio. For example, if the ratio you're trying to solve for involves 12 people with $36 among them and you're trying to find the ratio of dollars to people, the numbers are 36 and 12.

Determine the greatest common factor for both of the numbers in your ratio. This is the largest number that can be divided into both numbers equally. For example, if your first number is 36 and your second number is 12, the greatest common factor would be 12 because that's the largest number that divides both values evenly.

Enter your first number into the calculator. In the example, you would enter the total amount of money, 36.

Press the "Divide" button on your calculator and then enter the greatest common factor, which you found in Step 2. Hit the "=" button. Write this number down. In the example, 36 divided by 12 equals 3.

Enter the second number in your ratio. In the example, you would enter 12.

Press the "Divide" button and then enter the greatest common factor. Press the "=" button. Write this number down. In the example, 12 divided by 12 equals 1.

Express your ratio using the number in Step 3 and the number in Step 5. In the example, the ratio is 3:1. The ratio of dollars to people is 3:1.