How can I randomly select a number of cells and display the contents in a message box?

Question

I have a list of ID numbers 1101-1137 in cells A1-A37. I would like to click a button to randomly select 20 of these, with no repetitions, and display them in a message box.

Answer 1

If you construct a string containing the IDs already found through randomization, you can check for repeats.

Dim i As Long, msg As String, id As String

msg = Chr(9)
For i = 1 To 20
    id = 1100 + Int((37 - 1 + 1) * Rnd + 1)
    Do Until Not CBool(InStr(1, msg, Chr(9) & id & Chr(9)))
        Debug.Print id & msg
        id = 1100 + Int((37 - 1 + 1) * Rnd + 1)
    Loop
    msg = msg & id & Chr(9)
Next i
msg = Mid(Left(msg, Len(msg) - 1), 2)

MsgBox msg