int j;
String m1= "What radius do you want";
String m2= "Your area is";
float pi=3.14;
float r;
float Area;
int time=500;
void setup() {
  // put your setup code here, to run once:
Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
Serial.print(m1);

while (Serial.available()==0){

}
r=Serial.parseFloat();
Serial.println(r);

Serial.print(m2);
Area=pi*r*r;
Serial.println(Area);
Serial.println();
Serial.read();
}