title: Simple checksum algorithm
body: <p>Array a of ints contains the digits of a number. For this example I'll insert random numbers but the code must work for any set of numbers. I have to add together the ints in the array and then store the last digit in that sum into a variable called checksum.</p>
  
  <p>In this example, 3 + 5 + 7 = 15 so checksum would = 5. Here's my code so far. How would I go about calculating the checksum?</p>
  
  <pre><code>int[] a = { 3, 5, 7 }; 
  
  int checksum = 0;
  int i = 0;
  
  while ( i &lt; a.length )
      {
          checksum += a[i];
          i++;
      }
  
  checksum = ???????;
  </code></pre>