Question 22
To set the timer on his microwave oven, Rick enters the digits of the hours, minutes and seconds from left to right. For example, entering “12345” sets 1 hour 23 minutes 45 seconds, while “408” sets 4 minutes 8 seconds. One day, Rick accidentally missed the last digit and the timer finished 4 minutes 42 seconds earlier than he expected. What was the missing digit?