title: bcmath seems to give the wrong answer to my calculation
body: <p>I am not sure what I am doing wrong but this calculation</p>
  
  <pre><code>bcscale(20);
  echo bcmul(bcdiv('422218', '2388865'), '473');
  </code></pre>
  
  <p>echoes "83.59999999999999999670" but every other calculator gives me 83.6.</p>
  
  <p>Is there a way to solve this or is it a flaw in bcmath?</p>