I've got this quite basic code running on an Arduino Mega 2560, and the output is looking like I have the serial settings wrong, though I can't work out what to change.

```
void setup()  
{
  Serial.begin(9600);
  Serial.println("test123");
}

void loop()
{
  Serial.println("test" + millis());
}

```

The output looks like this:

```
ð¦·Z©÷
×ï¾üÿ7ß^|ïüûÿVÏuØëo~ìÿÓûzëýÿ{ßþ©×xñ×¤¿ïßûÏûýoÏ¿îãõI
õfwi÷`p¬½Ïª»QáÀª»¦·ð¦·Z©÷
test123
D

4ñjü¯÷~µÞMz¹Ý~¼
Ûþ}iû}ÒÖ­¦Ç¿÷ÿÂï½Õ¾;îö

```

I'm using the inbuilt "Serial Monitor" in the Arduino suite with settings 9600 baud and no line endings.

I see that the first println in `setup()` is sending the data as expected but all other comms are coming through as nonsense.

Any suggestions of what to do?