int maxNumber = 5, sum = 0, i;
void setup() {
  Serial.begin(9600);
  for (i = 0; i < maxNumber; i++) {
    Serial.println("Enter another number:");
    while (Serial.available() == 0);
    int num = Serial.parseInt();
    sum = sum + num;
  }
  Serial.print("Average = ");
  Serial.println(sum / 5.0);
}
void loop() {
}