Gash - you are absolutely correct, however, that requires the HHMM data to be entered as HH:MM rather than HH.MM which is what is going on (i.e. the problem to be overcome)here I believe.
What we need to do here is to take a Base60 number and convert it to a Base10 number; then do the addition(s) to provide a Base10 total; then convert that total to a Base60 number.
Still working on it; will get there today i hope!
[ 13 August 2001: Message edited by: Icarus ]