The easiest way to convert a test score to a percentage is to first divide the number of correct answers by the number of total questions. Then, multiplying this ratio by 100 percent gives the percentage score.
For example, if there are 25 questions on a test and a student gets 22 of them correct, then the test score percentage is (22/25) * 100 = 88 percent. If the number of questions the student answered correctly is not known, but the number answered incorrectly is known, an alternative method of calculation is ((total questions - number wrong) / total questions) * 100 percent. In the example above, the student would have gotten three questions incorrect; therefore, the test score percentage is calculated as ((25 - 3) / 25) * 100 = 88 percent.