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What should come in place of the question mark (?) in the given series? 21, 57, 87, 111, 129, ?
Question

What should come in place of the question mark (?) in the given series?
21, 57, 87, 111, 129, ?

A.

136

B.

143

C.

139

D.

141

Correct option is D

Given: 21, 57, 87, 111, 129, ?
Logic: Differences decrease by 6 each time.
57 - 21 = 36
87 - 57 = 30
111 - 87 = 24
129 - 111 = 18
Differences:
36, 30, 24, 18, 12 → decreasing by 6
Next term:
129 + 12 = 141
So, the missing term is 141.
Thus, correct option is (d).

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