Which of the following numbers will replace the question mark (?) in the given series?
31, 32, 36, ?, 61, 86

Correct option is C

The given series is: 31, 32, 36, ?, 61, 86
Step-by-step analysis:
31 → 32: The difference is 1, which is 1².
32 → 36: The difference is 4, which is 2².
Following the pattern of square differences, the next difference should be 3² = 9.
36 + 9 = 45.
Next, let’s check the rest of the series:
45 → 61: The difference is 16, which is 4².
61 → 86: The difference is 25, which is 5².
This confirms the pattern is correct.
The missing number is 45.
So, the correct answer is (c) 45.