How to avoid redirecting the form? - PERL

I have a form which I used to make a basic calculator but at the time of executing the script CGI in PERL redirects me to a white page and only prints the answer.

I would like to press the submit button to execute the script CGI of PERL and without changing the page I would print the answer below the button submit or in some space of the page without this to be redirected to the white page.

My form is this:

 <form id="formu" action="multiplicar.cgi" method="POST" class="form register">
  <h2 class="form_titulo"> Calculadora </h2> 
     <div class="contenedor-inputs">
      <br>
      <input type="text" name="numero1"  id="nombre" placeholder="Ingresa el número  " maxlength="10" class="input-100" required    />  
      <center>
       <select name="operador">
           <option value="sumar">+</option>
           <option value="restar">-</option>
           <option value="multiplicar">x</option>
           <option value="dividir">/</option>
       </select>
       </center>
       <input type="text" name="numero2"  id="nombre" placeholder="Ingresa el número  " maxlength="10" class="input-100" required    />   
<center>
   <input class="form-btn" type="submit" id="btnenviar" value="Ingresar"/>
       </center>
     </div>
  </form>

And the script CGI of PERL is the following:

#!"C:\xampp\perl\bin\perl.exe"

use strict;' #se utiliza el modo estricto de perl
use CGI;' #Libreria CGI de perl
# Recoge los parametros del formulario
my $cgi = new CGI;
my $n1 = $cgi->param('numero1');
my $n2 = $cgi->param('numero2');
my $op = $cgi->param('operador');


# comprueba si los parametros son numeros
if ($n1 !~ /[0-9]+$/ or $n2 !~ /[0-9]+$/ ) {
  print $cgi->header("text/html");
  print "Error ha ingresado datos incorrectos";
  return;
}
# declara variable total
my $total;

# se verifica la opción que el usuario eligio para mostrar el resultado
if($op eq "sumar"){
  $total=$n1+$n2;
}elsif($op eq "restar"){
  $total=$n1-$n2;
}elsif($op eq "multiplicar"){
  $total=$n1*$n2;
}elsif($op eq "dividir"){
if($n2<=0){
  $total="No se puede dividir entre 0"
}else{
  $total=$n1/$n2;}
}

# cabecera http
print $cgi->header("text/html");

#muestra el resultado

print "El resultado es " . $total;