Which number should replace the question mark (?) in the following number series?
39, 42, 48, 57, 69, ?, 102
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 84.
39 + 3 = 42; 42 + 6 = 48; 48 + 9 = 57; 57 + 12 = 69; 69 + 15 = 84; 84 + 18 = 102