A digital clock displays hours and minutes in 24-hour format (00:00 to 23:59). At how many unique times during a single day is the sum of the digits of the hour equal to the sum of the digits of the minute?
104
The hour digits sum can range from 0 to 1+9 = 10. For each possible hour digit sum, we count how many minute combinations (from 00 to 59) share that exact same digit sum, then sum those counts across all valid hours of the day.
About this riddle
Logic riddles give you a few facts and ask what must be true. List what you know, cross out what cannot be, and see what is left.
Difficulty: Hard. More like this: Logic riddles with answers or try Einstein's Logic Grid for a different kind of puzzle.
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