How to change a number from poisitve to negative based on text in another cell?

Im looking for a formula that would make a number change to negative if a word is present in the cell to the left.
If the cell to the left ="sell" number to the right will be changed to negative.

My attempt:
=IF(A1="sell",-(B1),(B1))

I want the answer to appear in B1

The problem is that it claims to be a circular reference.
Any suggestions?
Thanks

I'm new to posting, but have a year or so of work experience in Excel.

Yes, what you are suggesting would be what Excel calls a "circular reference".
This essentially means that the formula in a cell (b1), contains a reference to itself (b1).

The easiest fix to this problem is to place your actual values in column c, having your formula (in b1) reference that column (c1).

=IF(A1="sell",-(c1),(c1))

Hope that helps!