Treat cells with 0 and empty value differently

Hello,

Cell value 0 is blank
Cell value 0.00 is blank
Cell value empty is also blank

How to treat cell with 0 value and empty cells differently?

All the following forumas are returning result for both the {Buy} cells that has zero value and the {Buy} cells that are empty.

I want result only for the cells that has 0 or more value not the cells that has empty values.

IF(AND(IF({Buy} >= -1, TRUE(), FALSE()),{Sell}), (Sell-Buy)*Lot*Qty)
IF(AND(IF(NOT({Buy} = 0), TRUE(), FALSE()),{Sell}), (Sell-Buy)*Lot*Qty)
IF(AND(IF({Buy} = BLANK(),  FALSE(), TRUE()),{Sell}), (Sell-Buy)*Lot*Qty)