4 Digit Arduino Counter

//4 Digit Arduino Counter
#define A A4
#define B 13
#define C 10
#define D 9
#define E 8
#define F A1
#define G 11
// Pins driving common anodes
#define CA1 12
#define CA2 A3
#define CA3 A2
#define CA4 A5
// Pins for A B C D E F G, in sequence
const int segs[7] = {A4, 13, 10, 9, 8, A1, 11};
// Segments that make each number
const byte numbers[10] = {0b1000000,0b1111001,0b0100100,0b0110000,0b0011001,0b0010010,0b0000010,0b1111000,0b0000000,0b0010000};


void setup() {
  pinMode(A4, OUTPUT);
  pinMode(13, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(8, OUTPUT);
  pinMode(A1, OUTPUT);
  pinMode(11, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(A3, OUTPUT);
  pinMode(A2, OUTPUT);
  pinMode(A5, OUTPUT);
}
void loop() {
  for (int digit1=0; digit1 < 10; digit1++) {
    for (int digit2=0; digit2 < 10; digit2++) {
      for (int digit3=0; digit3 < 10; digit3++) {
        for (int digit4=0; digit4 < 10; digit4++) {
      unsigned long startTime = millis();
      for (unsigned long elapsed=0; elapsed < 600; elapsed = millis() - startTime) {
       lightDigit1(numbers[digit1]);
        delay(5);
 lightDigit2(numbers[digit2]);
        delay(5);
        lightDigit3(numbers[digit3]);
        delay(5);
        lightDigit4(numbers[digit4]);
        delay(5);
       }
       }
      }
      }
      }
    }
 void lightDigit1(byte number)      {
  digitalWrite(CA1, LOW);
  digitalWrite(CA2, LOW);
  digitalWrite(CA3, LOW);
  digitalWrite(CA4, HIGH);
  lightSegments(number);
 }
void lightDigit2(byte number) {
  digitalWrite(CA1, LOW);
  digitalWrite(CA2, LOW);
  digitalWrite(CA3, HIGH);
  digitalWrite(CA4, LOW);
  lightSegments(number);
}
void lightDigit3(byte number) {
  digitalWrite(CA1, LOW);
  digitalWrite(CA2, HIGH);
  digitalWrite(CA3, LOW);
  digitalWrite(CA4, LOW);
  lightSegments(number);
}
void lightDigit4(byte number){
  digitalWrite(CA1, HIGH);
  digitalWrite(CA2, LOW);
  digitalWrite(CA3, LOW);
  digitalWrite(CA4, LOW);
  lightSegments(number);

}
void lightSegments(byte number){
  for (int i = 0;i < 7;i++) {
    int bit = bitRead(number, i);
    digitalWrite(segs[i], bit);
  }
}