Most class grades are made up of several categories: homework, classwork, tests/quizzes, and the final exam. Usually, each category is worth a percentage of your overall grade. But because your final exam isn't scored until the very end, it isn't included when calculating your current overall grade. Instead, all the other categories are scaled up to consume the weight reserved for the final exam.
Required = (Goal − Current × (100% − Final Weight)) / Final Weight
See the formula sheet for an explanation of this formula and other formulas used in this calculator. It's not rocket science, it's just math! You could, of course, do this on any calculator, but you're here on RogerHub because it's cool. (:
Try one of the different calculator modes listed above. The advanced mode handles many different kinds of situations, such as: