Identify the number that does NOT belong to the following series.
81, 54, 36, 27, 22
Answer & explanation
Correct answer: option 4
81 - 54 = 27 ( it is divisible by 9)
54 -36 = 18 ( it is divisible by 9)
36- 27 = 9 ( it is divisible by 9)
27 - 22 = 5 ( it is not divisible by 9) (odd)