OraQA

The following is an interesting problem posted by mathforum.org:

Find the smallest number, M, such that:

M/10 leaves a remainder of 9;
M/9 leaves a remainder of 8;
M/8 leaves a remainder of 7;
M/7 leaves a remainder of 6;
M/6 leaves a remainder of 5;
M/5 leaves a remainder of 4;
M/4 leaves a remainder of 3;
M/3 leaves a remainder of 2;
M/2 leaves a remainder of 1.

variable input number
exec :input := 10

——————-SQL Solution —————–

SELECT MIN (num)
  FROM (SELECT   num
            FROM (SELECT     LEVEL num
                        FROM DUAL
                  CONNECT BY LEVEL <= (SELECT EXP (SUM (LN (l)))
                                         FROM (SELECT     LEVEL l
                                                     FROM DUAL
                                               CONNECT BY LEVEL <= :input))) a,
                 (SELECT     LEVEL div
                        FROM DUAL
                  CONNECT BY LEVEL <= :input) b
           WHERE MOD (a.num, b.div) = b.div - 1
        GROUP BY num
          HAVING COUNT (*) = :input)

MIN(NUM)
----------
2519

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