This type of calculation is best approached as a fraction.

The partial value, in this case 7, is divided by the total value. Formatting is then used to display the resulting number as a percentage.

In the example below, 7 answers were correct out of a possible 12.

Finally, change the format of the answer so that Excel displays it as a percentage. This can be done using the percentage icon on the toolbar.

It is usually worthwhile increasing the number of decimal places displayed so that a more accurate value is shown.

A score of 7 correct out of 12 questions represents a total score of 58.33%.

Try it yourself using the examples below...