For many students the most dreaded part of a test is discovering their final score. However, if one pays close attention to the number of possible questions missed during the exam, a single mathematical calculation can be used to determine the final grade. When the test contains 33 questions, this odd number can make the math slightly more difficult than calculating a test grade from an even number of questions. However, by using a calculator and a mathematical formula, the process is actually quite simple.
Write down the number of questions you missed.
Subtract the number written down in question one from 33. Use your calculator if necessary. For example, if you missed four questions, you would get 29. Write this number down.
Divide the number in Step two by 33 using your calculator. For example, if you missed four questions and wrote down 29 in Step two, you would divide 29 by 33 and get the decimal number 0.878787879 on your calculator.
Multiply the decimal number obtained in Step three by 100. Continuing with the above example from Step three, you would get the decimal number 87.878787879.
Round the decimal number obtained in Step four to the nearest one. To do this, if the number just to the right of the decimal is between zero and four, round to the lower one. If the number just to the right of the decimal is between five and nine, round to the higher one. Thus, for 87.878787879, since the number to the right of the decimal is eight, the rounded number would be 88.
TL;DR (Too Long; Didn't Read)
If your school uses a letter grading system, find where your rounded percentage falls in the grading rubric to assign a letter grade. For example, 80-89 is typically given the letter grade B, so an 88 would be a B.