Which of the following numbers will replaced the quesiton mark (?) in the given series?
21, 15, 9, 3, -3, ?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. -9.
Given series: 21, 15, 9, 3, -3, ?
21 - 6 = 15; 15 - 6 = 9; 9 - 6 = 3; 3 - 6 = -3; -3 - 6 = -9