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Excel: Generate Unique Random Numbers

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This UDF will generate x unique random numbers between any 2 numbers you specify. Many thanks to J.E. McGimpsey for modifying this to work on more than 10 numbers.

The Code

Function RandLotto(Bottom As Integer, Top As Integer, _

                    Amount As Integer) As String

    Dim iArr As Variant

    Dim i As Integer

    Dim r As Integer

    Dim temp As Integer

    

    Application.Volatile

    

    ReDim iArr(Bottom To Top)

    For i = Bottom To Top

        iArr(i) = i

    Next i

    

    For i = Top To Bottom + 1 Step -1

        r = Int(Rnd() * (i - Bottom + 1)) + Bottom

        temp = iArr(r)

        iArr(r) = iArr(i)

        iArr(i) = temp

    Next i

    

    For i = Bottom To Bottom + Amount - 1

        RandLotto = RandLotto & " " & iArr(i)

    Next i

    

    RandLotto = Trim(RandLotto)

    

End Function

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To use this UDF push Alt+F11 and go Insert>Module and paste in the code. Push Alt+Q and save. The Function will appear under "User Defined" in the Paste Function dialog box (Shift+F3). Use the Function in any cell as shown below. 

=RandLotto(1,20,8)
This would produce 8 unique random numbers between 1 and 20

 

See also:

Prevent Save As in Excel

Prevent Excel Being Saved With Another Name

Prevent Save Prompts in Excel

Excel VBA: Determine Number of Pages to be Printed

Protect/Lock Excel VBA Code

 

See also Index to Excel VBA Code and Index to Excel Freebies and Lesson 1 - Excel Fundamentals and Index to how to… providing a range of solutions.

 

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