Example of what it is doing:
1 A B
2 540.00 -60.00 Formula in Column B: =A2-600
3 700.00 100.00
=A3-600
4 -600.00
=A4-600
5 -600.00
=A5-600
6 -600.00
=A6-600
7 Total -1760.00

What is the correct formula for Column "B" where there will be no value in
"B" unless there is a value in Column "A"?

Example of what I would like for it to do:
1 A B
2 540.00 -60.00 Formula in Column B: =A2-600
3 700.00 100.00
=A3-600
4 0.00
=A4-600
5 0.00
=A5-600
6 0.00
=A6-600
7 Total 40.00

Thanks for your assistance.

Rodney