Concept:Identify even digits that are immediately preceded by a perfect square (
1,4,9) and immediately followed by an even digit (
0,2,4,6,8).
Explanation:The given series:
3,1,3,9,6,3,4,1,1,5,6,9,9,6,8,9,7,5,6,6,2.
Count from left to right only.
The pattern is: perfect square → even digit (target) → even digit.
First, list all even digits in the series: positions 5 (6), 7 (4), 11 (6), 14 (6), 15 (8), 19 (6), 20 (6), 21 (2).
Check each for the required neighbours:
• Position 5: preceded by 9 (perfect square), followed by 3 (odd) → fails.
• Position 7: preceded by 3 (not square) → fails.
• Position 11: preceded by 5 (not square) → fails.
• Position 14: preceded by 9 (perfect square), followed by 8 (even) → qualifies.
• Position 15: preceded by 6 (not square) → fails.
• Position 19: preceded by 5 (not square) → fails.
• Position 20: preceded by 6 (not square) → fails.
• Position 21: preceded by 6 (not square) → fails.
Only one such even digit meets the condition.
Answer:1
