char digit[] = {0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x7,0x7F,0x6F};

void setup() {
  randomSeed(analogRead(A0));
  DDRD = 0xFF;
}

void loop() {
  PORTD = digit[random(0,10)];
  delay(500);
}