int sensorValue = 0;
int outputValue = 0;

void setup()
{
  pinMode(A0, INPUT);
  pinMode(3, OUTPUT);
  pinMode(4, OUTPUT);
  pinMode(5, OUTPUT);
  pinMode(6, OUTPUT);
  Serial.begin(9600);

}

void loop()
{
  // read the analog in value:
  sensorValue = analogRead(A0);
  // map it to the range of the analog out:
  outputValue = map(sensorValue, 0, 1023, 0, 99);

  // light up left digit
  if(outputValue >= 0 && outputValue <= 9){
    digitalWrite(3, LOW);
    digitalWrite(4, LOW);
    digitalWrite(5, LOW);
    digitalWrite(6, LOW);
  }
  if(outputValue >= 10 && outputValue <= 19){
    digitalWrite(3, HIGH);
    digitalWrite(4, LOW);
    digitalWrite(5, LOW);
    digitalWrite(6, LOW);
  }
  if(outputValue >= 20 && outputValue <= 29){
    digitalWrite(3, LOW);
    digitalWrite(4, HIGH);
    digitalWrite(5, LOW);
    digitalWrite(6, LOW);
  }
  if(outputValue >= 30 && outputValue <= 39){
    digitalWrite(3, HIGH);
    digitalWrite(4, HIGH);
    digitalWrite(5, LOW);
    digitalWrite(6, LOW);
  }
  if(outputValue >= 40 && outputValue <= 49){
    digitalWrite(3, LOW);
    digitalWrite(4, LOW);
    digitalWrite(5, HIGH);
    digitalWrite(6, LOW);
  }
  if(outputValue >= 50 && outputValue <= 59){
    digitalWrite(3, HIGH);
    digitalWrite(4, LOW);
    digitalWrite(5, HIGH);
    digitalWrite(6, LOW);
  }
  if(outputValue >= 60 && outputValue <= 69){
    digitalWrite(3, LOW);
    digitalWrite(4, HIGH);
    digitalWrite(5, HIGH);
    digitalWrite(6, LOW);
  }
  if(outputValue >= 70 && outputValue <= 79){
    digitalWrite(3, HIGH);
    digitalWrite(4, HIGH);
    digitalWrite(5, HIGH);
    digitalWrite(6, LOW);
  }
  if(outputValue >= 80 && outputValue <= 89){
    digitalWrite(3, LOW);
    digitalWrite(4, LOW);
    digitalWrite(5, LOW);
    digitalWrite(6, HIGH);
  }
  if(outputValue >= 90 && outputValue <= 99){
    digitalWrite(3, HIGH);
    digitalWrite(4, LOW);
    digitalWrite(5, LOW);
    digitalWrite(6, HIGH);
  }

  // light up right digit
  if(outputValue % 10 == 0){
    digitalWrite(7, LOW);
    digitalWrite(8, LOW);
    digitalWrite(9, LOW);
    digitalWrite(10,LOW);
  }
  if(outputValue % 10 == 1){
    digitalWrite(7, HIGH);
    digitalWrite(8, LOW);
    digitalWrite(9, LOW);
    digitalWrite(10, LOW);
  }
  if(outputValue % 10 == 2){
    digitalWrite(7, LOW);
    digitalWrite(8, HIGH);
    digitalWrite(9, LOW);
    digitalWrite(10, LOW);
  }
  if(outputValue % 10 == 3){
    digitalWrite(7, HIGH);
    digitalWrite(8, HIGH);
    digitalWrite(9, LOW);
    digitalWrite(10, LOW);
  }
  if(outputValue % 10 == 4){
    digitalWrite(7, LOW);
    digitalWrite(8, LOW);
    digitalWrite(9, HIGH);
    digitalWrite(10, LOW);
  }
  if(outputValue % 10 == 5){
    digitalWrite(7, HIGH);
    digitalWrite(8, LOW);
    digitalWrite(9, HIGH);
    digitalWrite(10, LOW);
  }
  if(outputValue % 10 == 6){
    digitalWrite(7, LOW);
    digitalWrite(8, HIGH);
    digitalWrite(9, HIGH);
    digitalWrite(10, LOW);
  }
  if(outputValue % 10 == 7){
    digitalWrite(7, HIGH);
    digitalWrite(8, HIGH);
    digitalWrite(9, HIGH);
    digitalWrite(10, LOW);
  }
  if(outputValue % 10 == 8){
    digitalWrite(7, LOW);
    digitalWrite(8, LOW);
    digitalWrite(9, LOW);
    digitalWrite(10, HIGH);
  }
  if(outputValue % 10 == 9){
    digitalWrite(7, HIGH);
    digitalWrite(8, LOW);
    digitalWrite(9, LOW);
    digitalWrite(10, HIGH);
  }

  // print the results to the serial monitor:
  Serial.print("sensor = ");
  Serial.print(sensorValue);
  Serial.print("\t output = ");
  Serial.println(outputValue);
  // wait 2 seconds before the next loop for the
  // analog-to-digital converter to settle after the
  // last reading:
  delay(100); // Wait for 2 second(s)
}