FOR N% = 3 TO 6
        biased% = 0
        unbiased% = 0
        FOR I% = 1 TO 10000
          IF FNrandN(N%) biased% += 1
          IF FNunbiased(N%) unbiased% += 1
        NEXT
        PRINT "N = ";N% " : biased = "; biased%/100 "%, unbiased = "; unbiased%/100 "%"
      NEXT
      END

      DEF FNunbiased(N%)
      LOCAL A%,B%
      REPEAT
        A% = FNrandN(N%)
        B% = FNrandN(N%)
      UNTIL A%<>B%
      = A%

      DEF FNrandN(N%) = -(RND(N%) = 1)