If 1 is added to each odd digit and 2 is subtracted from each even digit in…

Concept

When a rule is applied to each digit independently, preserve the original order and transform one digit at a time.

For an odd digit d, use d + 1. For an even digit d, use d - 2. The position in the new number is then read from the unchanged left-to-right order.

Application

1. The first digit 6 is even, so 6 - 2 = 4.

2. The second digit 8 is even, so 8 - 2 = 6.

3. The third digit 4 is even, so 4 - 2 = 2.

4. The fourth digit 7 is odd, so 7 + 1 = 8.

5. The fifth digit 1 is odd, so 1 + 1 = 2.

6. The sixth digit 5 is odd, so 5 + 1 = 6.

7. The seventh digit 3 is odd, so 3 + 1 = 4.

Cross-check

The transformed digits in their original order are 4, 6, 2, 8, 2, 6, 4, giving 4628264. Reading from the left, its second digit is 6.

Result

The required digit is 6.