Number 5109238674: positions 1↔6, 2↔7, 3↔8, 4↔9, 5↔10 interchanged. 3rd digit from right?

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Number 5109238674: positions 1↔6, 2↔7, 3↔8, 4↔9, 5↔10 interchanged. 3rd digit from right? Answer: 9