program calc_av3_pascal;

uses crt;

var tecla : char;
    n1, n2 : real;

begin

  while ord ( tecla ) <> 27 do

  begin
    clrscr;

    writeln ( '>A< - Adicionar               >Q< - Quadrado' );
    writeln ( '>S< - Subtrair                >R< - Raiz Quadrada' );
    writeln ( '>D< - Dividir                 >F< - Fatorial' );
    writeln ( '>M< - Multiplicar           >ESC< - Fim' );
    writeln ( '' );
    write ( 'Escolha uma op‡ao indicada no destaque: ' );
    tecla := readkey;
    write ( tecla );

    case upcase ( tecla ) of
      'A': begin
            writeln ( '' );
            writeln ( '' );
            writeln ( 'Opera‡ao: Adi‡ao!' );
            writeln ( '' );
            write ( 'Digite o primeiro n£mero: ' );
            readln ( n1 );
            write ( 'Digite o segundo n£mero: ' );
            readln ( n2 );
            writeln ( '' );
            writeln ( 'Resultado:' );
            writeln ( '' );
            write ( n1:0:2, ' + ', n2:0:2, ' = ', n1 + n2:0:2 );
            readln;
    	   end;
      'S': begin
            writeln ( '' );
            writeln ( '' );
            writeln ( 'Opera‡ao: Subtra‡ao!' );
            writeln ( '' );
            write ( 'Digite o primeiro n£mero: ' );
            readln ( n1 );
            write ( 'Digite o segundo n£mero: ' );
            readln ( n2 );
            writeln ( '' );
            writeln ( 'Resultado:' );
            writeln ( '' );
            write ( n1:0:2, ' - ', n2:0:2, ' = ', n1 - n2:0:2 );
            readln ();
           end;
      'D': begin
            writeln ( '' );
            writeln ( '' );
            writeln ( 'Opera‡ao: Divisao!' );
            writeln ( '' );
            write ( 'Digite o primeiro n£mero: ' );
            readln ( n1 );
            write ( 'Digite o segundo n£mero: ' );
            readln ( n2 );
            writeln ( '' );
            writeln ( 'Resultado:' );
            writeln ( '' );
            write ( n1:0:2, ' / ', n2:0:2, ' = ', n1 / n2:0:2 );
            readln ();
           end;
      'M': begin
            writeln ( '' );
            writeln ( '' );
            writeln ( 'Opera‡ao: Multiplica‡ao' );
            writeln ( '' );
            write ( 'Digite o primeiro n£mero: ' );
            readln ( n1 );
            write ( 'Digite o segundo n£mero: ' );
            readln ( n2 );
            writeln ( '' );
            writeln ( 'Resultado:' );
            writeln ( '' );
            write ( n1:0:2, ' * ', n2:0:2, ' = ', n1 * n2:0:2 );
            readln ();
           end;
      'Q': begin
            writeln ( '' );
            writeln ( '' );
            writeln ( 'Opera‡ao: Elevar ao quadrado!' );
            writeln ( '' );
            write ( 'Digite o n£mero: ' );
            readln ( n1 );
            writeln ( '' );
            writeln ( 'Resultado:' );
            writeln ( '' );
            write ( n1:0:2, ' ao quadrado ‚ igual a ', sqr(n1):0:2 );
            readln ();
           end;
      'R': begin
            writeln ( '' );
            writeln ( '' );
            writeln ( 'Opera‡ao: Raiz quadrada!' );
            writeln ( '' );
            write ( 'Digite o n£mero: ' );
            readln ( n1 );
            writeln ( '' );
            writeln ( 'Resultado:' );
            writeln ( '' );
            write ( 'A raiz quadrada de ', n1:0:2, ' ‚ ', sqrt(n1):0:2 );
            readln ();
           end;
      'F': begin
            writeln ( '' );
            writeln ( '' );
            writeln ( 'Opera‡ao: Fatora‡ao!' );
            writeln ( '' );
            write ( 'Digite o n£mero a ser fatorado: ' );
            readln ( n1 );
            writeln ( '' );
            n2 := n1 - 1;
            writeln ( 'Fatorando o n£mero : ', n1:0:2 );
            writeln ( '' );
            while  ( n2 > 1 ) do
              begin
                writeln ( n1:0:2, ' * ', n2:0:2, ' = ', n1 * n2:0:2 );
                n1 := n1 * n2;
                n2 := n2 -1;
              end;
            writeln ( '' );
            write ( 'Resultado: ', n1:0:2 );
            readln ();
           end;
    end;
  end;

  writeln ( '' );
  writeln ( '' );
	write ( 'Fim de programa, pressione qualquer tecla para sair' );
  readkey;

end.