Phil,

Here's another, less repetitive code, version. Also I think there was a typo
in your post, the AV and AY seemed to get mixed. This is adjusted for that

Private Sub Worksheet_Change(ByVal Target As Range)
Dim row As Long

row = Target.row
'Test if it is a 'month'
If row = 19 And row <= 30 Then
'Test target column
Select Case Target.Column
Case 21: ' Column "U"
SetValue Target.Value, row, "X", 10
Case 30: ' Column "AD"
SetValue Target.Value, row, "AG", 11
Case 39: ' Column "AM"
SetValue Target.Value, row, "AP", 12
Case 48: ' Column "AV"
SetValue Target.Value, row, "AY", 13
End Select
End If
End Sub

Private Sub SetValue(val, row As Long, col As String, valueRow As Long)
Cells(row, col).Value = ((val - Range("V" & valueRow).Value) / _
(Range("P1" & valueRow).Value - Range("V1" &
valueRow).Value))
End Sub


--

HTH

Bob Phillips
... looking out across Poole Harbour to the Purbecks
(remove nothere from the email address if mailing direct)

"Bob Phillips" wrote in message news:...
Phil,

Sorry I missed a value. Try this instead
Private Sub Worksheet_Change(ByVal Target As Range)
Dim row As Long

row = Target.row
'Test if it is a 'month'
If row = 19 And row <= 30 Then
'Test target column
Select Case Target.Column
Case 21: ' Column "U"
Cells(row, "X").Value = _
((Target.Value - Range("V10").Value) / _
(Range("P10").Value - Range("V10").Value))
Case 30: ' Column "AD"
Cells(row, "AG").Value = _
((Target.Value - Range("V11").Value) / _
(Range("P11").Value - Range("V11").Value))
Case 39: ' Column "AM"
Cells(row, "AP").Value = _
((Target.Value - Range("V12").Value) / _
(Range("P12").Value - Range("V12").Value))
Case 48: ' Column "AY"
Cells(row, "AV").Value = _
((Target.Value - Range("V13").Value) / _
(Range("P13").Value - Range("V13").Value))
End Select
End If
End Sub

--

HTH

Bob Phillips
... looking out across Poole Harbour to the Purbecks
(remove nothere from the email address if mailing direct)

"Bob Phillips" wrote in message
news:...
Hi Phil,

I think that this is what you want

Private Sub Worksheet_Change(ByVal Target As Range)
Dim row As Long

row = Target.row
'Test if it is a 'month'
If row = 19 And row <= 30 Then
'Test target column
Select Case Target.Column
Case 21: ' Column "U"
Cells(row, "X").Value = _
((Target.Value - Range("V10").Value) / _
(Range("P10").Value - Range("V10").Value))
Case 30: ' Column "AD"
Cells(row, "AG").Value = _
((Target.Value - Range("V10").Value) / _
(Range("P11").Value - Range("V11").Value))
Case 39: ' Column "AM"
Cells(row, "AP").Value = _
((Target.Value - Range("V10").Value) / _
(Range("P12").Value - Range("V12").Value))
Case 48: ' Column "AY"
Cells(row, "AV").Value = _
((Target.Value - Range("V10").Value) / _
(Range("P13").Value - Range("V13").Value))
End Select
End If
End Sub


--

HTH

Bob Phillips
... looking out across Poole Harbour to the Purbecks
(remove nothere from the email address if mailing direct)

"Phil Hageman" wrote in message
...
In this code (located in the worksheet code area), I need
to expand things further. As it is now, cells P10 and V10
work with two ranges: U19:U30, and X19:X30, to calculate
values for the "X" range cells. I need to add three more
sets of cells/ranges:

P10, V10, 9:U30 and X19:X30 (existing code)
P11, V11, AD19:AD30 and AG19:AG30 (New. AD = Column 30)
P12, V12, AM19:AM30 and AP19:AP30 (New. AM = Column 39)
P13, V13, AV19:AV30 and AY19:AY30 (New. AY = Column 48)

Option Explicit
Private Sub Worksheet_Change(ByVal Target As Range)
Dim row As Long
row = Target.row
'Test target column
If Target.Column = 21 Then ' Column "U"
'Test if it is a 'month'
If row = 19 And row <= 30 Then
Cells(row, "X").Value = _
((Target.Value - Range("V10").Value) / _
(Range("P10").Value - Range("V10").Value))
End If
End If
End Sub