Using Excel 2007.

I am fairly new to Excel and need some assistance.

I am wanting to create a spreadsheet with one cell that has a constant value
that will be used to calculate a total with other cells.

Example:

A1 times (constant value cell A7)
A2 times (constant value cell A7)
A3 times (constant value cell A7)
A4 times (constant value cell A7)

What I am having to do is change the "constant value cell" location every
time I copy the original cell that has the formula.

Example:

First cell = A1*A7. If I copy this cell to A2, the fomula will change to
A2*F8. I then have to change the F8 back to the "constant value cell"
location F7.

My question is this. Is there a way to, for the lack of a better way to
describe it, lock the "constant value cell" location in a formula so I don't
have to change it every time I copy the formula to a different cell.

I hope this explains my situation.

Thanks for any help.