const unsigned int scan[] = {5, 6, 7, 8};
#define DATA 10
#define LATCH 11
#define CLK 12

byte numbers[] = {
  0xC0, 0xF9, 0xA4, 0xB0, 0x99, 
  0x92, 0x82, 0xF8, 0x80, 0x90
};

void setup() {
  for (int i = 0; i < 4; i++) {
    pinMode(scan[i], OUTPUT);
    digitalWrite(scan[i], HIGH);
  }
  pinMode(DATA, OUTPUT);
  pinMode(LATCH, OUTPUT);
  pinMode(CLK, OUTPUT);
}

void setDigits(int number, int digits[4]) {
  for (int i = 0; i < 4; i++) {
    digits[i] = number % 10;
    number /= 10;
  }
}

void loop() {
  static int number = 0;
  static unsigned long checkpoint = 0;
  static int digits[4];
  for (int i = 0; i < 4; i++) {
    digitalWrite(LATCH, LOW);
    shiftOut(DATA, CLK, MSBFIRST, numbers[digits[i]]);
    digitalWrite(LATCH, HIGH);
    digitalWrite(scan[i], LOW);
    delay(1);
    digitalWrite(scan[i], HIGH);
  }
  if (millis() - checkpoint > 200) {
    number++;
    setDigits(number, digits);
    checkpoint = millis();
  }
}