int ledPin =3;

void setup() {
  // put your setup code here, to run once:
  pinMode(ledPin, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  //1 2 3 4 5 6+++++++++++
  for(int i=0; i <10; i++){
   digitalWrite(ledPin, HIGH);
   delay(i*100);
   digitalWrite(ledPin, LOW);
   delay(i*100);
  }
}