int a = 2, b = 3, c = 4, d = 5, e = 6, f = 7, g = 8;

void setup()
{
  pinMode(a, OUTPUT);
  pinMode(b, OUTPUT);
  pinMode(c, OUTPUT);
  pinMode(d, OUTPUT);
  pinMode(e, OUTPUT);
  pinMode(f, OUTPUT);
  pinMode(g, OUTPUT);  
}

void display(int n)
{
  if(n == 0 || n == 2 || n == 3 || n == 5 || n == 6 || n == 7 || n == 8 || n == 9)
    digitalWrite(a, HIGH);
  else digitalWrite(a, LOW);

  if(n == 0 || n == 1 || n == 2 || n == 3 || n == 4 || n == 7 || n == 8 || n == 9)
    digitalWrite(b, HIGH);
  else digitalWrite(b, LOW);

  if(n == 0 || n == 1 || n == 3 || n == 4 || n == 5 || n == 6 || n == 7 || n == 8 || n == 9)
    digitalWrite(c, HIGH);
  else digitalWrite(c, LOW);

  if(n == 0 || n == 2 || n == 3 || n == 5 || n == 6 || n == 8 || n == 9)
    digitalWrite(d, HIGH);
  else digitalWrite(d, LOW);

  if(n == 0 || n == 2 || n == 6 || n == 8)
    digitalWrite(e, HIGH);
  else digitalWrite(e, LOW);

  if(n == 0 || n == 4 || n == 5 || n == 6 || n == 8 || n == 9)
    digitalWrite(f, HIGH);
  else digitalWrite(f, LOW);

  if(n == 2 || n == 4 || n == 5 || n == 6 || n == 8 || n == 9)
    digitalWrite(g, HIGH);
  else digitalWrite(g, LOW);
}

void loop()
{
  for(int i = 0; i <= 9; i++)
    display(i);
  delay(100);
}