SQL> with v  as (select level c from dual connect by level<=100)
  2  select v1.c a ,v2.c b, v3.c c
  3   from v v1, v v2 ,v v3
  4  where (v1.c||v2.c )= to_number(v2.c||v3.c||v3.c)/2 ;

         A          B          C
---------- ---------- ----------
         6          1          2
        11         22          4
        12          2          4
        18          3          6
        22         44          8
        24          4          8
        30         61          2
        41         83          6

8 rows selected