SQL> create or replace procedure test_194 (p_in  in  number
  2                                       ,p_out out number) as
  3  begin
  4    p_out := p_in;
  5  end;
  6  /

Procedure created.

SQL> 
SQL> set serveroutput on size 10000
SQL> 
SQL> declare
  2    v_num    number;
  3  begin
  4    test_194 (10.3,v_num);
  5    
  6    dbms_output.put_line('Return value '||v_num);
  7  end;
  8  /
Return value 10.3

PL/SQL procedure successfully completed.