void setup() {
  pinMode(A0, INPUT);
  Serial.begin(9600);
  for (int pin = 3 ; pin <= 12 ; pin++) pinMode(pin, OUTPUT);
 
}
void loop() {
  int data = analogRead(A0);
  float resolution = 5.0 / 1023 ;
  float volt = data * resolution ;
  Serial.print("Data = " + String(data));
  Serial.println("\t Volt= " + String(volt));
  for (int pin = 3 ; pin <= 12 ; pin++) digitalWrite(pin, LOW);
  float d = 5.0 / 10 ; // delta = 0/5
  int n = volt / d ;  // LED number
  digitalWrite(3 + n, HIGH);
  delay(100);
}