title: HTML calculator , + doesnt works
body: <p>I made a calculator, but <code>+</code> doesn't work, why?? -> if you want + something, you have to press button : sečíst   .... it doesn't + it, but it writes it in some bad way, take a look :  <a href="http://jsfiddle.net/p77roqhr/" rel="nofollow">http://jsfiddle.net/p77roqhr/</a></p>
  
  <pre><code>&lt;pre&gt;
  &lt;!DOCTYPE html&gt; 
  &lt;html lang="cs-CZ"&gt; 
      &lt;head&gt;
          &lt;meta charset="UTF-8"&gt;
          &lt;meta name="generator" content="Prace"&gt; 
          &lt;link rel="stylesheet" href="online_kalkulacka.css"&gt;
          &lt;title&gt;kalkulačka&lt;/title&gt; 
      &lt;/head&gt; 
      &lt;body&gt;        
          &lt;h1&gt;Kalkulačka&lt;/h1&gt;
          &lt;form name="kalkulacka"&gt;
              &lt;fieldset&gt;
                  &lt;div id="cislo1"&gt;
                      &lt;label for="vypln_cislo1"&gt;zadej zde první číslo&lt;/label&gt; &lt;input id="1" type="number" name="prvni" min="0" max="10000"&gt;
                  &lt;/div&gt;
                  &lt;div id="cislo2"&gt;
                      &lt;label for="vypln_cislo2"&gt;zadej zde druhé číslo&lt;/label&gt; &lt;input id="2" type="number" name="druhe" min="0" max="10000"&gt;
                  &lt;/div&gt;
                      &lt;button id="b1" onclick="document.getElementById('3').innerText = document.getElementById('1').value + document.getElementById('2').value; return false;"&gt;sečíst&lt;/button&gt;
                      &lt;button id="b2" onclick="document.getElementById('3').innerText = document.getElementById('1').value - document.getElementById('2').value; return false;"&gt;odečíst&lt;/button&gt;
                      &lt;button id="b3" onclick="document.getElementById('3').innerText = document.getElementById('1').value / document.getElementById('2').value; return false;"&gt;vydělit&lt;/button&gt;
                      &lt;button id="b4" onclick="document.getElementById('3').innerText = document.getElementById('1').value * document.getElementById('2').value; return false;"&gt;vynásobit&lt;/button&gt;
                  &lt;div id="vysledek"&gt;
                      výsledek je : 
                      &lt;br&gt;
                      &lt;div id="vysledek2"&gt;
                          &lt;span id="3"&gt;&lt;/span&gt;
                      &lt;/div&gt;
                  &lt;/div&gt;
              &lt;/fieldset&gt;
          &lt;/form&gt;
      &lt;/body&gt; 
  &lt;/html&gt;
  
  &lt;/pre&gt;
  </code></pre>