Here is a loop that will add odd numbers to listbox1 and even numbers to listbox2:
vb Code:
  1. For j = 1 To 12
  2.     For i = 1 To 31
  3.         Randomize
  4.         x = Int(Rnd * 13 + 1)
  5.         winner(j, i) = x
  6.         If j / 2 = int(j / 2) Then
  7.             ListjEven.AddItem winner(j, i)
  8.         Else
  9.             ListjOdd.AddItem winner(j, i)
  10.         EndIf
  11.     Next i
  12. Next j