int potpen=A0;
int readvalue;
float voltage;
void setup() {
  // put your setup code here, to run once:
  pinMode(potpen, INPUT);
  Serial.begin(9600);

}

void loop() {
  // put your main code here, to run repeatedly:
  readvalue = analogRead(potpen);
  voltage=(5.0/1023.0)*readvalue;
  Serial.println(voltage);
  delay(250);

}