const int dataPin  = 2;   // DS
const int clockPin = 3;  // SHCP
const int latchPin = 4;  // STCP
int count;
const int numeral[] { // segment bit positions: abcdefgp
  0b11111100,   // 0
  0b01100000,   // 1
  0b11011010,   // 2 
  0b11110010,   // 3
  0b01100110,   // 4
  0b10110110,   // 5
  0b00111110,   // 6
  0b11100000,   // 7
  0b11111110,   // 8
  0b11110110,   // 9
  0b00000001,   // dp
};

void setup() {
  pinMode(dataPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(latchPin, OUTPUT);
}

void loop() {
  if (count > 9)
  count = 0;

  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, LSBFIRST, numeral[count]); // display count
  digitalWrite(latchPin, HIGH);
  delay(500);

  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, LSBFIRST, numeral[count] | numeral[10]); // add decimal point
  digitalWrite(latchPin, HIGH);
  delay(500);

  count++;
}