program Procedure_Type_Example;

{$F+}        (* This forces far calls and is required by TURBO *)

             (* Pascal to use a procedure type.                *)
type Procedure_Type = procedure(In1, In2, In3 : integer;

                                var Result    : integer);
var Number1, Number2, Number3 : integer;

    Final_Result              : integer;

    Do_Math                   : Procedure_Type;
   procedure Add(In1, In2, In3 : integer;

                 var Result    : integer);

   begin

      Result := In1 + In2 + In3;

      Writeln('The sum of the numbers is    ',Result:6);

   end;
   procedure Mult(In1, In2, In3 : integer;

                  var Result    : integer);

   begin

      Result := In1 * In2 * In3;

      Writeln('The product of the numbers is',Result:6);

   end;
   procedure Average(In1, In2, In3 : integer;

                     var Result    : integer);

   begin

      Result := (In1 * In2 * In3) div 3;

      Writeln('The Average of the numbers is',Result:6);

   end;
begin

   Number1 := 10;

   Number2 := 15;

   Number3 := 20;
   Do_Math := Add;

   Do_Math(Number1, Number2, Number3, Final_Result);
   Do_Math := Mult;

   Do_Math(Number1, Number2, Number3, Final_Result);
   Do_Math := Average;

   Do_Math(Number1, Number2, Number3, Final_Result);

end.

Result of execution
The sum of the numbers is        45

The product of the numbers is  3000

The average of the numbers is  1000