I6, 06, 68, 88, ?, 98
We turn that upside-down
86 '¿ '88 '89 '90 '9I
Then obviously we can tell that ¿ is to be replaced by 87
86 '87 '88 '89 '90 '9I
Then we turn it back right-side up again, and we have:
I6, 06, 68, 88, L8, 98
Answer: L8 J
Answer is 87 If you look from the top from the right to left then series is 86, 87, 88, 89, 90, 91.