(* circle.pas - This program will find the area of the circle whose
 * radius is supplied by the user.
 * Later on, we could modify the program by having it also compute
 * the circumference.
 * By default, Pascal will print real numbers in scientific notation.
 * When using a real variable in a write/writeln statement, if you
 * say value:x:y, the value is printed in a space of x characters with
 * y digits of precision.  If x is not wide enough, then Pascal will override.
 * This may cause any text appearing later on the line to appear farther to
 * the right than you originally planned.
 * If you only supply one number after the colon, as in value:x, then
 * you are not supplying the precision, only the amount of space to print.
 *)
 
program circle;

const
  pi = 3.1415926535;

var
  radius, area : real;

begin
  write('What is the radius of the circle?  ');
  readln(radius);
  
  area := pi * radius * radius;
  
  writeln('The area of the circle is ', area:5:2);

end.