If you view the Moderate Quiz page while a student is currently taking a quiz, the Time column shows the running time for the quiz. When time has expired, the Time column displays the submission as Time Up!
For non-timed quizzes, the timer counts down to the quiz Until date. If no Until date is set for the quiz, the quiz defaults to the course end date. The highest number display is in months, days, hours, minutes, and seconds.
Note: When students are taking a non-timed quiz, their timer will show the elapsed time counting up.