What number would replace the question mark in the series 2, 9, 20, 35, 54, 77, ?, 135

A131

B104 ✓ Correct

C125

D98

Correct answer: (B) 104

Explanation

The missing term is 104.

differences are 7, 11, 15, 19, 23.

each gap rises by 4.

next gap = 23 + 4 = 27, so 77 + 27 = 104.

check: 104 + 31 = 135, matching the last term.

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