automatically working formula

[alex dihes]

how to have a formula working automatically periodically, like: every 5 minutes from 8:00 til 16:00 add 1 to a number in the cell?

[shg]

You'll need to use VBA.

See Help for the OnTime method.

[shg]

Maybe like this.

In ThisWorkbook:

Private Sub Workbook_Open()
    Application.OnTime Date + TimeValue("08:00"), "AddOneEveryFive"
End Sub

In a code module:

Sub AddOneEveryFive()
    With Range("A1")
        If IsNumeric(.Value) Then .Value = .Value + 1
    End With
    
    If Time < TimeValue("15:55") Then
        Application.OnTime Now + TimeValue("00:05"), "AddOneEveryFive"
    End If
End Sub