I am aware that Excel can modify the appearance of a cell content, using "Format cells". When I enter "20000" in a cell, and I use "Format cells", more exactly "Date", Type "14/03/2012", I see "03/10/1954".

Now I would like to do just the opposite: I have quite a lot of cells, containing datetime stamps like "2017-10-09 01:56:39.466", and I would like to explain to Excel that this is a datetime format, to be interpreted as `YYYY-MM-DD hh:mm:ss.ttt`

(where `t`

stands for "thousands of seconds"). Is that possible?

The idea behind it is that I have a lot of those cells, and I would like to substract those datetime stamps in order to find out which was the entry with the longest duration, but as far as I know, substraction is only possible by number values, hence the need to make Excel understand the used format.

I'm working with Microsoft Excel 2016 MSO 32-bit.