I have data from a CSV file that lists several thousand date and time values.
It extends over a 72 hour period. The values listed in the cells are the
standard date and time values (i.e., 11/15/05; and 00:00:0). The time values
are reported in 1 second increments. In a nearby column, I would like to
create a rolling sum, starting with time "zero", and ending with total time
reported in hours (approximately 72). I need it in this format so I can
graph it logarithmically.

Can't seem to get any calc to work.

kp