title: Why don't I see the result in the table? area of a rectangle PHP
body: <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  &lt;head&gt;
      &lt;meta charset=&quot;utf-8&quot;&gt;
      &lt;title&gt;Calcular area del rectangulo&lt;/title&gt;
  &lt;/head&gt;
  &lt;body&gt;
      &lt;div class=&quot;contenedor&quot; &gt; 
            &lt;form  action=&quot;&lt;?php echo htmlspecialchars($_SERVER['PHP_SELF']); ?&gt;&quot;
              methode=&quot;post&quot;&gt;
              Base: &lt;input type=&quot;number&quot;class=&quot;formulario&quot; name=&quot;base&quot; 
              placeholder=&quot;Base&quot; value=&quot;&lt;?php if(isset($_POST['base'])){ echo $_POST['base'];} ?&gt;&quot;&gt; &lt;br&gt;
              Altura:&lt;input type=&quot;number&quot;class=&quot;formulario&quot; name=&quot;altu&quot; 
              placeholder=&quot;Altura&quot; value=&quot;&lt;?php if(isset($_POST['altu'])){ echo $_POST['altu'];} ?&gt;&quot;&gt; &lt;br&gt;
             &lt;input type=&quot;submit&quot; name=&quot;Calcular&quot; class=&quot;btn btn-cal&quot; value=&quot;Calcular&quot;&gt; &lt;br&gt;
  
            &lt;?php
  
             $post =(isset($_POST['base'])&amp;&amp;!empty($_POST['base']))&amp;&amp;(isset($_POST['altu'])&amp;&amp;!empty($_POST['altu']));
             if($post){
            $base=htmlspecialchars($_POST['base']);
            $altu=htmlspecialchars($_POST['altu']);
            $Area=($_POST['base'] * $_POST['altu']);
             }
            ?&gt;
            
  
            &lt;input type=&quot;number&quot; class=&quot;form-control&quot; name=&quot;area&quot; placeholder=&quot;area&quot; value=&quot;&lt;?=$Area?&gt;&quot;&gt;
          &lt;/form&gt;
  
        &lt;/div&gt;
        &lt;a href=&quot;index.php&quot;&gt;Menu principal&lt;/a&gt;&lt;br&gt;
      enter code here
  
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  <p>I have to calculate the area of a figure, I have everything done, but the problem is that when I calculate it, the result does not appear in the area.</p>