calculating from variable cells
I have a table where I am trying to calculate, among various parcels of land, how much each parcel is costing per acre. Each row is for a different parcel of land. In this table I am working with parcels under one acre and sometimes the information I am given is in acre size and sometimes in square footage. So column A is for square footage entries and Column B is for acreage size entries. Column C is for the cost of the parcel. When I enter square footage, right now, it takes that number and divides it by 43560 automatically populating column B cell with the acreage size (=8755/43560) to auto calculate .20 acres. It then takes the dollar cost and divides it by the acreage size to come up with the cost per acre - which is the end purpose. It is a little cumbersome the way it is now because when I have only the acreage size of a parcel I have to delete the formula from the cell first and manually type in the acreage size. I would like a way of doing this so that neither A nor B columns have formulas in them but if I type a square footage in A OR type in acreage in B and then enter the price for the parcel, the D column will take the price and then use whichever A or B cell has an entry and calculate the cost per acre. Of course, it will have to do an additional function where there is a square footage column A entry by converting it to acreage.
MacBook Pro 13", macOS 10.14