title: Does syntax of bash variables change when being passed to bc?
body: <p>I noticed a solution on Codewars which had the following syntax:</p>
  <pre><code>#!/bin/bash
  seven () {
      bc &lt;&lt;&lt; &quot;
      scale=0
      counter=0
      m=$1
      while( m &gt; 99 ) {
          counter = counter + 1
          x = m / 10
          y = m % 10
          m = x - 2 * y
      }
      print m, \&quot;, \&quot;, counter
      &quot;
  }
  seven &quot;$1&quot;
  </code></pre>
  <p>My question is regarding the variables used(m,x,counter). How is it that bash allows to use variables without using $variable_name?</p>
  <p>Are there special cases (such as wraping code with double-quotes) that allow for this?</p>