title: How is O(N) algorithm also an O(N^2) algorithm?
body: <p>I was reading about Big-O Notation </p>
  
  <blockquote>
    <p>So,  any algorithm that is O(N) is also an O(N^2).</p>
  </blockquote>
  
  <p>It seems confusing to me, I know that Big-O  gives upper bound only. </p>
  
  <p>But how can an O(N) algorithm also be an O(N^2) algorithm.</p>
  
  <p>Is there any examples where it is the case?</p>
  
  <p>I can't think of any.</p>
  
  <p>Can anyone explain it to me? </p>