Identify missing numbers

I need to be able to identify missing numbers that are in sequential order in column A. I would like to be able to run this so any missing number in column A will generate the missing number(s) in column B for my review.

I have to run this weekly and the starting numbers will change that I start from.

Ex. Week 1
column A Column B
455
456
457
459 458
461 460

Week 2
Column A Column B
15
16
17 18,19,20
21
22
25 23,24

I am using Excel 07 and I have very little experience with Excel.


Any help I can get is greatly appreciated.

Hi, Try this.
List in column "A", as yout post.
Results in column "B" as required.

Dim Nst As String, Fst As String, Diff As Integer, nu As Integer
Dim cl As Range, AllNu As String

For Each cl In Range(Range("A1"), _
    Range("A" & Rows.Count).End(xlUp))
   If IsNumeric(cl.Value) Then
     On Error Resume Next
    Fst = cl.Value

    Nst = cl.Offset(1, 0).Value
    
    If Val(Nst) > Val(Fst) Then
        If Not Val(Nst) = Val(Fst) + 1 Then
            Diff = Val(Nst) - Val(Fst)
    End If
         For nu = 1 To Diff - 1
              Val (Fst) + nu
                AllNu = AllNu & Val(Fst) + nu & ","
            Next nu
  cl.Offset(0, 1).Value = Left(AllNu, Len(AllNu) - 1)
       End If
    End If
AllNu = ""
Diff = 0
Next cl

Regards Mick

I hate to ask but can you explain how to use/run this code.

Thanks

I got it to work. Thanks so much.