hi
just too add a tad to what pete said.
excel keeps track of datese as a number based on the 1900/1904 date keeping
system and time as a decimal value of 1 day. so 5 minutes 8 seconds would be
0.003553241 of 1 day and would display in the formula bar as 12:05:08 AM or
5 minutes 8 seconds past midnight.
see this site for more details......
http://support.microsoft.com/kb/214330

to do the math. since excel views time as numbers you can just subtract one
time from another. with 5:08 in A2 and 10:15 in B2....
in c2 enter.....=B2-A2
which would yield 5:07
as to your last question, the 1900 date system will not display negative
numbers.
instead you get ####### any time the results are negative. you can use a
formula to prevent this..
=mod(C2-B2,1)
this would prevent the number from displaying negative but with the date
formated as mm:ss and desplayed as 12:05:08 AM in the formula bar, the
results would be unexpected since the results may put the time back past
midnight.
59:59 and displayed in the formula bar as 11:59:59 PM
yeah i know. wierd.
the 1904 date system will display negative numbers but switching would add 4
years and 1 day to all the other dates you may have in your other files. and
you might be out of sinc with other pc's. see the above site for more details.

regards
FSt1

"Eric Parker" wrote:

I have an Excel spreadsheet with mile split times for cross country runners
in one column (e.g. 5:08, meaning 5 minutes, 8 seconds) and 2 mile split
times in the next column (e.g. 10:15). The third column is the difference
between the mile and 2 mile times which is the time the runner ran for the
second mile. How can I have Excel do this calculation, and what format do I
need to put it in considering I do not need hours, days, dates, years, AM,
PM, etc.? I also would like to have a fourth column which displays the
difference (in seconds) between the third column and the first column, which
can be either a positive or a negative number to show how much the runner
sped up or slowed down.