I have a formula that totals a balance of columns C to F and I wish to copy
this formula down to line 1000. I am currently upto line 25 and lines 26 to
1000 shows the last balance, ie 1200 all the way down to line 1000.

The formula I am using is =H24-SUM(C25:F25)+G25

What can I add to this formula to show lines 26 to 1000 as blank or 0, but
will change when figures are entered in columns C-F.