title: Math on batch (win)
body: <p>I am developing a CMD batch.  I want to do some math in it. This formula: <code>(x+1)100:y</code></p>
  
  <p>So in batch, <code>x = %x%, and y = %y%</code>. I know how to set the variables. Now, how can batch calculate this? (WINDOWS CMD) </p>
  
  <p>Do I need something extra?</p>
  
  <p>(I need this to be available to users of Windows XP to 7.)</p>