Private Sub Worksheet_Change(ByVal Target As Range)

dim x as Integer
x=0

If Not Intersect(Target, Range("C50")) Is Nothing Then

       If Not IsEmpty(Cells(49, 3).Value) Then
            If x = 0 Then
                Cells(49, 3).Value = Cells(49, 3).Value + 0.8
                x = x+1
            End If

        End If

    End If
End Sub