initial serial monitor test . puzzled by response

[system]

Similarly the sketch

// sketch 03-04
void setup()
{
  Serial.begin(9600);
  int a = 2;
  int b = 49;
  int c = a + b;
  Serial.println(c); 
}
void loop()
{}

results in 551 in the serial monitor, the 5 appearing immediately followed shortly by 51