title: Understanding ibase and obase used
body: <p>I'm trying to solve the following exercise:</p>
  <blockquote>
  <p>Write a command line that takes numbers from variables FT_NBR1, in  ’\&quot;?! base, and FT_NBR2, in mrdoc base, and displays the sum of both in gtaio luSnemf base.</p>
  </blockquote>
  <p>I know the solution is:</p>
  <pre class="lang-bash prettyprint-override"><code>echo $FT_NBR1 + $FT_NBR2 | sed 's/\\/1/g' | sed 's/?/3/g' | sed 's/!/4/g' | sed &quot;s/\'/0/g&quot; | sed &quot;s/\&quot;/2/g&quot; | tr &quot;mrdoc&quot; &quot;01234&quot; | xargs echo &quot;ibase=5; obase=23;&quot; | bc | tr &quot;0123456789ABC&quot; &quot;gtaio luSnemf&quot;
  </code></pre>
  <p>I don't understand why ibase=5 and obase=23.</p>
  <p>I read about ibase and obase, and I understand this is a base conversion, from base 5 to base 23. Anyone can explain me why 5 and 23. Thank you</p>