long readTagID(const byte *data, const uint32_t numBytes) {
  char tempBuffer[numBytes + 1];       // create a temporary buffer enough bytes including  for a trailing null char
  memcpy(tempBuffer, data, numBytes);  // copy the bytes
  tempBuffer[numBytes] = '\0';         // add the trailing null char
  return atol(tempBuffer);             // parse the content as a long number and return it
}

byte testData[] = "1000 and some garbage here";
void setup() {
  Serial.begin(115200);
  Serial.print("\reading the data -> ");
  Serial.println(readTagID(testData, 4));
}

void loop() {}