This will change ALL data entered in column B (2) to negative values (code
courtesy of Bob Phillips).

HTH

Private Sub Worksheet_Change(ByVal Target As Range)

On Error GoTo ws_exit:
Application.EnableEvents = False
With Target
If .Column = 2 Then ' Change to required column
.Value = Value * -1
End If
End With

ws_exit:
Application.EnableEvents = True
End Sub

'This is worksheet event code, which means that it needs to be
'placed in the appropriate worksheet code module, not a standard
'code module. To do this, right-click on the sheet tab, select
'the View Code option from the menu, and paste the code in.

"JoeMNY" wrote:

Is there a way to enter a number in a cell and have the number automatically
appear as a negative number without entering "-" before it.

TIA
Joe