title: The result of the script to get the area value is wrong
body: <p>I wrote a script to find the area of the room, But The result is incorrect.</p>
  <p>In order to obtain the area of the room, except ceiling '
  (W of wall① * room height)*2 + (W of wall② * room height)*2 = total wall area value
  I wrote it as above.
  The floor area is when the checkbox is checked
  (W of wall① *W of wall②) + Total wall area value = Room area value excluding ceiling
  I wrote it so that it comes out as above, but the result value keeps coming out wrong.</p>
  <p>For example, if the W of the wall① is 4, the W of the wall② is 2, and the height is 3, the answer is 36 for the area excluding the floor area and the ceiling area.
  But it is extracted as 28.
  Naturally, even if you include the floor area value, the value is different.</p>
  <p>I'm still studying scripts and I don't really know what's wrong because I don't know very well.
  Help..!</p>
  <p>※I used a translator because I couldn't speak English. That is why my words may not be natural. Please understand.</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>function btnResult() {
      var MyWidth = eval(document.getElementById("Value01").value);
      var MyLength = eval(document.getElementById("Value02").value);
      var MyHeight = eval(document.getElementById("Value03").value);
   
      if (!MyWidth) {
          alert("Pelase, Check.");
          document.getElementById("Value01").focus();
          return false;
      } else if (!MyHeight) {
          alert("Pelase, Check.");
          document.getElementById("Value02").focus();
          return false;
      } else if (!MyLength) {
          alert("Pelase, Check.");
          document.getElementById("Value03").focus();
          return false;
      } else {
   
          var data01 = (MyWidth * MyHeight) * 2;
          var data02 = (MyLength * MyHeight) * 2;
          var data03 = MyWidth * MyLength;
   
          var TotalResult = data01 + data02;
   
          var addGCheck = $('.add_Ground').is(':checked');
   
          if (addGCheck) {
              TotalResult = data01 + data02 + data03;
          }
          document.getElementById("resultA").innerHTML = Number(TotalResult.toFixed(1));
      }
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/1.7.1/jquery.min.js"&gt;&lt;/script&gt;
  &lt;div id="Box"&gt;
      &lt;div class="Inner"&gt;
          &lt;div class="List"&gt;
              &lt;span class="Title"&gt;W&lt;/span&gt;
              &lt;input type="text" id="Value01" class="ValueBox"&gt;
              &lt;span class="Unit"&gt;m&lt;/span&gt;
          &lt;/div&gt;
          &lt;div class="List"&gt;
              &lt;span class="Title"&gt;L&lt;/span&gt;
              &lt;input type="text" id="Value03" class="ValueBox"&gt;
              &lt;span class="Unit"&gt;m&lt;/span&gt;
          &lt;/div&gt;
          &lt;div class="List"&gt;
              &lt;span class="Title"&gt;H&lt;/span&gt;
              &lt;input type="text" id="Value02" class="ValueBox"&gt;
              &lt;span class="Unit"&gt;m&lt;/span&gt;
          &lt;/div&gt;
           
          &lt;span class="addCheck"&gt;&lt;input type="checkbox" class="add_Ground" name="addGround"&gt;Add Ground&lt;/span&gt;
            
          &lt;div class="Btn"&gt;
              &lt;input type="button" id="btnSum" class="btnSum" value="value" onclick="btnResult()"&gt;
          &lt;/div&gt;
   
          &lt;div class="ValueCont"&gt;
              &lt;span class="ValueTitle"&gt;Total Value&lt;/span&gt;
              &lt;p id="resultA" class="resultValue"&gt;&lt;/p&gt;
              &lt;span class="ValueUnit"&gt;m&lt;sup&gt;2&lt;/sup&gt;&lt;/span&gt;
          &lt;/div&gt;
      &lt;/div&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>