Most date libraries count to 23h 59m 59s then roll over to 00h 00m 00s. So the answer is 23 hours, not 24.
Edit: I’m big dum dum. It’s asking string length of “Monday”, thus 6.
You’re also mistaken about the time too. The first second of the day is 00:00:00 the last second of the day is 23:59:59
That’s still a full and exact 24 hours.
Yes, it’s a full 24 hours, but a library doesn’t use 24:00:00 to represent the last hour, it’s 23:59:59. Once it hits 24:00, it rolls over to 00:00:00.
Hence my initial error of answering 23.
It’s not valid, but I don’t edit out erronous answers because I believe all data should be preserved, no matter how dumb it makes one look.