title: Addition for BigDecimal
body: <p>I want to do some simple sums with some currency values expressed in <code>BigDecimal</code> type. </p>
  
  <pre><code>BigDecimal test = new BigDecimal(0);
  System.out.println(test);
  test.add(new BigDecimal(30));
  System.out.println(test);
  test.add(new BigDecimal(45));
  System.out.println(test);
  </code></pre>
  
  <p>Obviously I do not understand well the <code>BigDecimal</code> arithmetics, see output behind.</p>
  
  <pre><code>Test
  0
  0
  0
  </code></pre>
  
  <p>Can anyone help me out?</p>