How to display zero value as blank cell in mac numbers 3.1

The easiest way is to use "Conditional Highlighting..." found under the "Format" menu.

Select the cell you want to have blank as zero then select "Conditional Highlighting" you then set a highlight when the cell is equal to zero. Choose "Custom Highlighting" at the bottom of the style list and then you can set the text colour to white. A "blank" cell on zero.

Here's a simple approach: =If(A1<=0," ",A1)

You're simple saying: If the result displayed in Cell A1 is less than or equal to 0, display what's between the parenthesis. It could be Yes, No, Blue, Green, or just Blank space. If Cell A1 is greater than 0, display the value of that cell.

You don't have to leave a space between the "" for the formula to work. Try a simple test of the formula on different values and watch as the cell will switch to a Blank value, if the Cell is less than or equal to 0. Logic formulas using If, And, Or and If And switches are powerful tools in many calculations goals.