Some nights it is difficult to get to sleep. On one such night, John counted the number of LEDs (Light-Emitting Diodes) on his clock radio that was on to make each individual time from 10:00 PM to 12:59 AM. He did this instead of counting sheep. When it was 11:11, for example, he noted that 8 of the LEDs were on. During the time that John was awake from 10:00 PM to 12:59 AM, how many of the times had exactly 20 of the LEDs on?
Here is some information about John’s clock radio:
• Only times from 12:00 to 11:59 can be displayed.
• Each digit is made up of seven LEDs that are turned off or on depending on the particular digit to be displayed. The digit 2 has five of the seven LEDs on while the digit 8 has all seven LEDs on. All of the digits are shown in the diagram below.
• For times from 10:00 to 12:59, all four digits are used.
• For times from 1:00 to 9:59, only three digits are displayed. The leftmost digit is completely off for these times.