Hi everyone, this is my first time in a forum so I apologise if Ive already done something wrong!

Heres what I'm trying to do:

I have a value of 0:01:20.555 in a cell in the form of hh.mm.ss.111 and I want to get the adjacent cell to display that value in just seconds (ss.11 to be precise).

So say for example I used 0:01:20.555 (1 minute and 20.555 seconds). So the 1 minute is 60 seconds, so overall the time in seconds would be 80.55 (I need to round off to 2 decimal places instead of the previous 3).

Examples:
0:01:20.555 becomes 80.55.
01:00:00.000 becomes 3600.
0:02:01.111 becomes 121.11

Does anybody know how this can be done for a whole set of data? Many thanks guys!