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What number belongs at the question mark? 3, 4, 10, 33, ?, 685

Competition practiceNumber Series

A136
B132
C140
D128

Step-by-Step Solution

The rule is

\times 1 + 1, \times 2 + 2, \times 3 + 3

, ...: 3→4→10→33→

33 \times 4 + 4 = 136

, and

136 \times 5 + 5 = 685

checks.

Answer: A) 136

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