I recently encountered a problem that involves the calculation of the sum of all possible 5-digit numbers that can be formed from the digits {1, 3, 5, 7, 9}; each digit can only be used once withn each arrangement. What initially seemed to be a very daunting task was reduced to a much simpler one by resorting to some basic number theory; the solution to this problem is contained in the link directly below.

Adding Permutations

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