Creating a Plus/Minus Button

On some calculators there is a little button that can come in very handy: the plus/minus button. This button, when pressed, will switch whatever value is on the display between its positive and negative values. For instance, if the display shows the number 57, then pressing the button will change the display to -57. Pressing it again will switch the value back to 57.

If you would like a "button" that does this in Excel, you'll quickly find that there is none built into the program. You can quickly create one, however, by using a macro:

Sub PlusMinus1()
    Dim cell As Range

    For Each cell In Selection
        If Application.IsNumber(cell) Then
            cell.Value = cell.Value * -1
        End If
    Next cell
End Sub

Note that the macro simply steps through whatever range of cells you selected when the macro started. Each cell is checked to see if it contains a number. If it does, then the value of that number is multiplied by -1. The result is a switch in sign for the number.

One drawback to the macro is that if the cell contains a formula, that formula is converted to a value and then multiplied by the -1 value. You may not want to lose your formulas. In that case, you could rely on a more discriminating macro, one that checks to see if the cell contains a formula or not. If not, then it is simply multiplied by -1. If so, then the formula is adjusted so that the result is multiplied by -1.

Sub PlusMinus2()
    Dim cell As Range

    For Each cell In Selection
        If Left(cell.Formula, 1) = "=" Then
            Cell.Formula = cell.Formula & " * -1"
        Elseif Application.IsNumber(cell) Then
            cell.Value = cell.Value * -1
        End If
    Next cell
End Sub

You can assign either of these macros to a shortcut key or to a toolbar button to make it easy to use at any time.

ExcelTips is your source for cost-effective Microsoft Excel training. This tip (3256) applies to Microsoft Excel 97, 2000, 2002, and 2003. You can find a version of this tip for the ribbon interface of Excel (Excel 2007 and later) here: Creating a Plus/Minus Button.