When you wish to know how many questions a student answered correctly on a test you can use the percentile score to calculate the raw score. The raw score is the amount of questions answered correctly out of the total number of questions. You will need to know the number of questions on the test as well as the percentile score. This calculation will only work if all responses were weighted equally. The raw score will not be accurate if the student was given partial credit on some questions.

Divide the percentage score by 100 to calculate the fractional score. For example, if the score was 74 percent, the fractional score will be 0.74.

Multiply the fractional score by the number of questions on the test to calculate the number of questions that were answered correctly. This number is the raw score.

Determine how many questions the student missed by subtracting the raw score from the total number of questions.
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