title: how to do two complement multiplication and division of integers?
body: <p>I have read this <a href="https://stackoverflow.com/questions/3899401/binary-multiplication-2s-complement">post</a> on binary multiplication using two complement. but it is not very clear to me. Even I have difficulty understanding the <a href="http://en.wikipedia.org/wiki/Two%27s_complement#Multiplication" rel="noreferrer">wiki</a> article on this. I want to know how to go about calculating multiplications of negative numbers:</p>
  
  <pre><code>eg: -1 with -7 should give 7.
  A 4-bit, 2's complement of -1 is : 1111
  A 4-bit, 2's complement of -7 is : 1001
  </code></pre>
  
  <p>some step-wise way of calculating the multiplication will be helpful. No article I came across talks about division. How to approach this?</p>