Sub RangeColor()
Dim aRnd(), rRng As Range
Dim lVal As Long
Dim i As Long, j As Long
    Application.Calculate
    lVal = Cells(3, 6).Value

    If lVal > 0 Then
        ReDim aRnd(1 To 100)
        Randomize

        For i = 1 To 100
            j = Int(Rnd * i + 1)
            If j <> i Then aRnd(i) = aRnd(j)
            aRnd(j) = i
        Next i

        Set rRng = Cells(aRnd(1) + 1, 3)

        For i = 2 To lVal
            Set rRng = Union(rRng, Cells(aRnd(i) + 1, 3))
        Next i
    End If

    Application.ScreenUpdating = False
    Range("C2:C101").Interior.Color = RGB(200, 0, 0)
    If Not rRng Is Nothing Then rRng.Interior.Color = RGB(0, 200, 0)
    Application.ScreenUpdating = True

    Set rRng = Nothing
End Sub