title: How to make sure the input is a multiple of 16, and if not add padding to it
body: <p>basically i want to have an inputted message, and if it is not a valkue of 16 add random letters to it to make it a mulitple of 16</p>
  
  <p>this is my current code:</p>
  
  <pre><code>import math
  
  s = "IYGGRTOCTOERGTDKHUTAOHEIIATTOICNNRIHDSRGKENEACA!"
  i = 16
  rows = [s[x:x+i] for x in range(0, len(s), i)]
      #print('\n'.join(rows))
  columns = list(zip(*rows))
  print i, columns
  </code></pre>
  
  <p>This does nothing fancy and insteadjust splits the input up every 16 characters and takes the first letter from each coulmn then outputs it etc, a very basic transpoistion cypher</p>
  
  <p>so what i am trying to do it figure out if s is a multiple of 16, and if not add some random letters to s until it is
  so how can i achieve this in python ?</p>
  
  <p>thanks guys</p>