title: knitr displaying digits of an integer without scientific notation
body: <p>when displaying a number with inline-code with more than four digits like </p>
  
  <pre><code>`r 21645`
  </code></pre>
  
  <p>the result in a knitted html-file is this: <code>2.164510^{4}</code> (in reality inside the inline-hook there is a calculation going on which results in 21645). Even though I just want it to print the number, like so: <code>21645</code>. I can easily fix this for one instance wrapping it inside <code>as.integer</code> or <code>format</code> or <code>print</code>, but how do I set an option for the whole knitr-document so that it prints whole integers as such (all I need is to print 5 digits)? Doing this by hand gets very annoying. Setting <code>options(digits = 7)</code> doesnt help. I am guessing I would have to set some chunk-optionor define a <a href="http://yihui.name/knitr/hooks/" rel="noreferrer">hook</a>, but I have no idea how</p>