FWIW, tried this with two less common languages:<p><pre><code>    Tcl: + 0.1 0.2 
      0.30000000000000004

    Chicken Scheme: (+ 0.1 0.2)
      0.3
</code></pre>
Same results under Windows 8.1 and FreeBSD 10.2.  I suppose one is as &quot;right&quot; as the other, at least both answers equally popular among languages.