title: Why I am getting peculiar result?
body: <pre><code>$a=(float) 640.81;
  $b=(float) 636.85;
  $c=(float) 3.96;
  
  $d= $a-$b-$c;
  echo $d;
  </code></pre>
  
  <p>Why  am getting -7.7271522513911E-14 this value? It should be 0 right.</p>