Calculate minus figures only

i need to know how to do the following calculation. i need to calculate the
minus figures only and leave to positive figures. these figures are inserted
random so i cannot select specific cells. example as follows:

£-1500.00 these figures are inserted as random figures based on other data
entry
£ 2000.00 from differetn cells and calculated thus giving current balance.
£ 1246.00 i only need the minus figures calculated to show loss
£- 600.00

£ 2100.00 Total

Help most appreciated. i am using excell in office 2000.