[Java] Loop over digits in a number

Well of course we could just convert the number to String and take it up from there, but since we're real men who know about the modulo operator, we can instead do:

 while(number > 0) {  
  digit = number % 10;
  number /= 10; //discard the digit and advance to the next spot  
 }  

And would also be careful to declare number as a copy of our input number so as not to destroy it.