displaying total by adding +ve and -ve nos

[simi28]

Hi all
I have a a field in one of my ASP page.say margin
I want to add them and dispaly total.
for example
the field is margin
the data are £-2,192.27
£216.55
£42.06
£130.57
-12.50
23.90
45.00
-21.10
total ----------------
how camn i add the negative and positive nos
please help me.
Thanks