Other considerations
In addition to the whole complex of questions already discussed, other in- vestigations are possible, Given a number, instead of calculating the difference between the number and its mirror num ber, we can form the maximum and minimum numbers(ie, the largest and small est possible numbers, using the same digits as in the given number) and subtract them from each other, Then we continue this method, taking the maximum and mini mum numbers of each succeeding differ ence, as long as possible(fig. 3) As a result of the investigation of these sequences of differences, we find that almost all differences of this kind stop after few at the most five steps with 495. An exception is the case in which the max imum three-digit number has the condi- tion h u 0 or h u 1 In carrying out this activity, a complete list of the"number of steps" for all three digit numbers can easily be obtained