int mq3_analogPin = A0; // connected to the output pin of MQ3 

void setup()
{
  Serial.begin(9600); // open serial at 9600 bps
}

void loop()
{
  // give ample warmup time for readings to stabilize
  int mq3_value = analogRead(mq3_analogPin);
  Serial.println(mq3_value);
  delay(100); //Just here to slow down the output.
}