List Tutorial Exercise 9
------------------------

Step one is to convert our integer into vector notation.

     1:  25129925999           3:  25129925999
         .                     2:  10
                               1:  [11, 10, 9, ..., 1, 0]
                                   .

         25129925999 RET           10 RET 12 RET v x 12 RET -

     1:  25129925999              1:  [0, 2, 25, 251, 2512, ... ]
     2:  [100000000000, ... ]         .
         .

         V M ^   s 1                  V M \

(Recall, the `\' command computes an integer quotient.)

     1:  [0, 2, 5, 1, 2, 9, 9, 2, 5, 9, 9, 9]
         .

         10 V M %   s 2

Next we must increment this number.  This involves adding one to the
last digit, plus handling carries.  There is a carry to the left out
of a digit if that digit is a nine and all the digits to the right of
it are nines.

     1:  [0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 1]   1:  [1, 1, 1, 0, 0, 1, ... ]
         .                                          .

         9 V M a =                                  v v

     1:  [1, 1, 1, 0, 0, 0, ... ]   1:  [0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1]
         .                              .

         V U *                          v v 1 |

Accumulating `*' across a vector of ones and zeros will preserve only
the initial run of ones.  These are the carries into all digits except
the rightmost digit.  Concatenating a one on the right takes care of
aligning the carries properly, and also adding one to the rightmost
digit.

     2:  [0, 0, 0, 0, ... ]     1:  [0, 0, 2, 5, 1, 2, 9, 9, 2, 6, 0, 0, 0]
     1:  [0, 0, 2, 5, ... ]         .
         .

         0 r 2 |                    V M +  10 V M %

Here we have concatenated 0 to the *left* of the original number; this
takes care of shifting the carries by one with respect to the digits
that generated them.

Finally, we must convert this list back into an integer.

     3:  [0, 0, 2, 5, ... ]        2:  [0, 0, 2, 5, ... ]
     2:  1000000000000             1:  [1000000000000, 100000000000, ... ]
     1:  [100000000000, ... ]          .
         .

         10 RET 12 ^  r 1              |

     1:  [0, 0, 20000000000, 5000000000, ... ]    1:  25129926000
         .                                            .

         V M *                                        V R +

Another way to do this final step would be to reduce the formula
`10 $$ + $' across the vector of digits.

     1:  [0, 0, 2, 5, ... ]        1:  25129926000
         .                             .

                                       V R ' 10 $$ + $ RET