title: Calculate information within form view
body: <pre><code>&lt;%= f.label :months, "Experience" %&gt;
  &lt;%= f.hidden_field :months, :value =&gt; (params[:Years]*12) + params[:Months] %&gt;
  &lt;%= number_field_tag "Years", nil, placeholder:"Years" %&gt; Years &lt;%= number_field_tag "Months", nil, placeholder:"Months" %&gt; Months
  </code></pre>
  
  <p>As above;  I'd like to calculate and pass the information needed. Currently I error on the * method:</p>
  
  <pre><code>undefined method `*' for nil:NilClass
  </code></pre>
  
  <p>Any advice will be helpful.</p>