问题
I'm currently using the custom format, m:ss.00, and it works perfectly for any times that exceed one minute, e.g. 1:02.47. However, if I enter a time less than a minute, e.g. 57.66, it gets transformed into 50:24.00. I can get around this by entering 0:57.66, but I'd rather not have to always type the leading 0: and I don't want the leading 0: displayed anyway. I'd like for it to understand that if I skip the number followed by a colon part, to interpret this as no minutes and simply display 57.66.
回答1:
In Excel datetimes:
1 = 1 day
...therefore:
1 / 24 = 1 hour = 0.04166667 formatted as m:ss.00 is 0:00.00
1 / 24 / 60 = 1 minute = 0.00069444 formatted as m:ss.00 is 1:00.00
1 / 24 / 60 / 60 = 1 second = 0.00001157 formatted as m:ss.00 is 0:01.00
So if you have a number of seconds like 50.24, you can convert it to Excel DateTime by dividing it by x/24/60/60 which is the same as x/86400.
This will convert it to seconds.
The reason your method works if it's more than a minute is basically through the process of elimination. A "real number" like 50.24 just looks like a number since it has no : colon or anything else to distinguish it as a datetime. Entering intead 0:50.24 will force Excel to recognize it as a datetime.
Similarly, entering these dates:
12/01/1999
01/12/1999
...could have varying results (January 12, 1999 or December 1, 1999) depending on your regional settings (whether your country uses M/D/Y or D/M/Y), however, entering either of these:
01/13/1999
13/01/1999
...will both be interpreted as "January 1, 1999" since Excel was able to eliminate other possibilities (since there's no 13th month).
More Information:
Office.com : Working with Dates & Times in Excel
Office.com : Change the Windows Regional Settings
Wikipedia : Date format by Country
Office.com : Add or Subtract Time
来源：https://stackoverflow.com/questions/50317179/timespan-formatting-in-excel