Digit swap in pairs – For 3597280164, interchange (1↔6), (2↔7), (3↔8), (4↔9), (5↔10). After rearrangement, which digit is fourth from the right end?

Introduction / Context:We perform specified swaps on a 10-digit number and then read off a position from the right side.

Given Data / Assumptions:

• Original digits (1-based): [3,5,9,7,2,8,0,1,6,4].
• Swap pairs: (1,6), (2,7), (3,8), (4,9), (5,10).

Concept / Approach:After swaps, compute the final sequence and convert “fourth from right” to left index 7 (since 10 - 4 + 1 = 7).

Step-by-Step Solution:After swaps: [8,0,1,6,4,3,5,9,7,2].Fourth from right = position 7 = 5.

Verification / Alternative check:Rightmost positions: 1st→2, 2nd→7, 3rd→9, 4th→5. Consistent with the computed sequence.

Why Other Options Are Wrong:3/4/9 are present but not at the specified right-based index.

Common Pitfalls:Mis-mapping right-based positions to left indices; mixing the order of swaps or applying swaps cumulatively on already swapped positions incorrectly.

Final Answer:5