Although not mentioned in the article, the trick can handle this. The rule should be "remove a digit that isn't 0", and if the sum of remaining digits is divisi

Although not mentioned in the article, the trick can handle this. The rule should be "remove a digit that isn't 0", and if the sum of remaining digits is divisible by 9 then the removed digit must be 9 as well. That will cover everything except the case when the original number and the scrambled number are the same.