The phrase "curve the exam" can describe several different policies. A calculator cannot predict the adjusted score until the instructor identifies the method.
Additive curve
The same number of points is added to every raw score, often with a maximum of 100.
Rescale the highest score to 100
One rescaling method divides each raw score by the highest score and multiplies by 100. If the highest score is 92, a raw 78 becomes:
Change letter-grade cutoffs
An instructor can leave numeric scores unchanged and lower the thresholds for A, B, C, and other grades. In that case, the curved letter changes while the percentage shown may stay at 78.
Distribution-based curves
Some courses assign target proportions of letter grades or use statistical measures. These methods require the full class distribution, not only one student's score. For example, Loyola University Chicago School of Law publishes a distribution curve for certain course sizes, illustrating that a formal curve can control grade proportions rather than add points.
Compare curve methods on the same score
For a raw 78, adding five points gives 83, while scaling against a highest score of 92 gives 84.78. Lowering the B cutoff to 78 could instead change only the letter. Showing these side by side prevents the word "curve" from hiding the rule that produced the outcome.
If the class uses a distribution, an individual score is insufficient. You would need at least the full score set or the instructor's published grade proportions and tie-handling policy.
Do not promise a curve
Class averages and rumors do not establish the instructor's rule. Use a provisional scenario and label the method, cap, and assumed highest score.