title: Returning the value to input
body: <p>From input i enter numbers in the input text, then i have 5 buttons that have functions on them i tried to make the first button to minus the number by 1 but i don't know when i click the number get -1 but it doesn't show changes to the input box. How can i fix this i mean don't know how to do it because i tried using <code>number.innerHTML = number-=1</code> but it doesn't work ? Here is my html and javascript code:</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>var number = document.getElementById("number");
  number = number.value;
  
  function minus() {
    number.value = number -= 1;
    console.log(number);
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;!DOCTYPE html&gt;
  &lt;html lang="en"&gt;
  
  &lt;head&gt;
    &lt;meta charset="UTF-8"&gt;
    &lt;meta name="viewport" content="width=device-width, initial-scale=1.0"&gt;
    &lt;title&gt;Document&lt;/title&gt;
  &lt;/head&gt;
  
  &lt;body&gt;
  
    &lt;div&gt;
      &lt;input type="text" id="number" id="output"&gt;
      &lt;input type="button" value="&lt;" onclick="minus();"&gt;
      &lt;input type="button" value="&gt;" onclick="plus();"&gt;
      &lt;input type="button" value="FLIP" onclick="flip();"&gt;
      &lt;input type="button" value="STORE" onclick="store();"&gt;
      &lt;input type="button" value="CHECK" onclick="check();"&gt;
    &lt;/div&gt;
  
  &lt;/body&gt;
  
  &lt;/html&gt;</code></pre>
  </div>
  </div>
  </p>