title: Homework: how to write own multiplication of big numbers?
body: <p>In my project I have to deal with multiplication of big numbers ( greater then java.long ) stared in my own <code>BigNumber</code> class as <code>int[]</code>. Basically I need to implement something like this :</p>
  
  <pre><code>    157 x
      121 y
     ----
      157 result1
     314  + result2
    157   + result3
   ------
   18997  finalResult
  </code></pre>
  
  <p>But how do I implement it?</p>
  
  <p>I thought about expanding result2,3 with zeros (3140, 15700) and adding them. But first I somehow need to navigate between each digit of y and multiply it by each digit of x.</p>