Arduino Multi-Digit Serial Input

/****
* Alternate Multi-digit inputs for serial
* by:  James Lewis (jamesC4S), [email protected]
*
* Instead of using ATOI, this example uses simple math.
*****/

float receivedNumber=0;

void setup() {
  Serial.begin(9600);
}

void loop() {
  if (Serial.available() > 0) {
      int A = Serial.read();   // read() only returns 1 byte at a time

      if (A == 13)  {  // Did the user press enter?
        Serial.println(receivedNumber, 0);
        receivedNumber=0.0;
      }

      // skip anything that isn't an integer
      if ((A >= 48) && (A <= 57))
          receivedNumber = receivedNumber * 10 + A-48;
      }
}