Custom Formatting - Issue with Months

[Demonsguile]

I'm trying to do something that I had thought simplistic, but the formatting of the result is causing me issues.
A1 = 1/8/2018 23:10
A2 = 1/8/2018 23:29

A3 contains the formula =A2-A1.
Then, I am formatting it with the following custom format: yy\y mm\m dd\d hh:mm:ss

I am expecting to see 00y 00m 00d 00:19:00 as only 19 minutes have elapsed between the two times.
What I'm getting is 00y 01m 00d 00:19:00. I have no idea where the 01 is coming from.

Any help would be appreciated.

Thank you.

 

[pgc01]

Hi

Datetime in excel does not start at 0, it starts at year 1900

Ex. write 2 in a cell and format it as yyyy-mm-dd. You'll see 1900-01-02

You'd probably guessed it you you'd have used 4 year digit in your format: yyyy\y mm\m dd\d hh:mm:ss

Please try