One way:

Public Sub JoinNegs()
Dim rCell As Range
For Each rCell In Range("A1:A" & _
Range("A" & Rows.Count).End(xlUp).Row)
With rCell
If .Offset(0, 1).Text = "-" Then _
.Value = -.Value
End With
Next rCell
End Sub

In article <5b153e053bbd9@uwe,
"Danny Boy via OfficeKB.com" <u15117@uwe wrote:

Thanks for your responses

I don't have the option to use any of those methods,

I have cell A1 = 10 and B1 = -

This must change A1 to -10

I have no other option, I cannot use any other cells for joining,

Any others Ideas?