title: How to check if a number is a multiple of 6?
body: <p>I would like an alogrithm that would use only shift, add or subtract operations to find whether a number is a multiple of 6.  So, basically just binary operations.</p>
  
  <p>So far I think I should logical right shift the number twice to divide by 4 and then subtract 6 once from it.  But I know something is wrong with my approach and cannot figure out what.  </p>