title: How can I decrease the value of a variable by 0.2 every 5 minutes?
body: <p>How can I decrease the value of a  variable by 0.2 every 5 minutes?</p>
  
  <p>I have a variable <code>var = 7.2</code>. Now I added a button so when I <kbd>click</kbd> on it the variable will increment by 1.</p>
  
  <p>Now I want to add an option where the variable decrement by 0.2 every 5 minutes and stop at the original number 7.2.</p>
  
  <p>I have already tried <code>window.setInterval()</code> without successs.</p>