2021 JMPSC Sprint Problems/Problem 10
Serena gets a grade of for her chapter test. She doesn't remember how many problems there were, but she remembers that there were at most problems, each problem solved correctly was worth an equal amount of points, and she did not receive any points for an incorrect or skipped question. Find the sum of all the possible numbers of problems that the test could have had.
Because , where is an integer. This implies that is a multiple of . The multiples of less than are , , , and , so the answer is .