Find the next number in the series:
10, 21, 43, 87, ?, 351
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 175.
10 × 2 + 1 = 20 + 1 = 21
21 × 2 + 1 = 42 + 1 = 43
43 × 2 + 1 = 86 + 1 = 87
87 × 2 + 1 = 174 + 1 = 175
175 × 2 + 1 = 350 + 1 = 351