[SOLVED]Logging multiple temp sensors questions(step by step)

I am going to suggest doing what PaulS recommended. This works on my Mega2560.

// include the freeRam function in your sketch
int freeRam() {
  extern int __heap_start,*__brkval;
  int v;
  return (int)&v - (__brkval == 0 ? (int)&__heap_start : (int) __brkval);  
}

void setup() {
  Serial.begin(9600);

  // then use it like this
  Serial.print("SRAM free: ");
  Serial.println(freeRam());  
}

void loop() {
}