Why i am getting error while executing pl/sql program?

CREATE TABLE areas
             (
              radius NUMBER(7),
              area   NUMBER(7,2)
             )

--- I have created pl/sql program to input radius, calculate area and insert values into areas table, the starting radius can be 3---

declare pi CONSTANT NUMBER(4,2) :=3.14;
        radius NUMBER(4);
        area   NUMBER(5,2);
BEGIN
  radius:=3;
  WHILE radius <=7
  LOOP
    area := pi*Power(radius,2);
    INSERT INTO areas VALUES (radius,
                              area)
    radius := radius+1
  END LOOP;
END;

Answer

In your code you are missing the semicolon in insert statement & radius value assignment statement –

declare pi CONSTANT NUMBER(4,2) :=3.14;
        radius NUMBER(4);
        area   NUMBER(5,2);
BEGIN
  radius:=3;
  WHILE radius <=7
  LOOP
    area := pi*Power(radius,2);
    INSERT INTO areas VALUES (radius,
                              area);
    radius := radius+1;
  END LOOP;
END;

Demo.