The following macro will do this for you - i can e-mail you this as an addin
is you want which will enable you to click on a toolbar button and use it in
any spreadsheet

Sub ShowFormulas()
Dim cell As Range
On Error Resume Next

Application.ScreenUpdating = False
Application.Calculation = xlCalculationManual

For Each cell In Cells.SpecialCells(xlCellTypeConstants)
If IsNumeric(cell.Value) Then
cell.Interior.ColorIndex = 4
End If
Next cell

Application.Calculation = xlCalculationAutomatic

End Sub