long randNumber;//the long keyword is 
//used to displayed  a long value on screen.
void setup() {
  Serial.begin(9600);
  randomSeed(analogRead(A0));
}

void loop() {
  Serial.print("random1=");
  randNumber=random(300);//will print random numbers up to 300. 
  Serial.println(randNumber);
  Serial.print("random2=");//will print random number starting From 10 to 20 in the range.
  randNumber=random(10,20);
  Serial.println(randNumber);
  delay(50);

}