Choose the number that will replace the question mark (?) in the following series.
7, 90, 14, 85, 28, 80, 56, ?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 75
The terms jump up and down, so read the terms in odd places and in even places as two separate series:
Odd places: 7, 14, 28, 56, each twice the one before
Even places: 90, 85, 80, ?, each 5 less than the one before
The question mark is in the 8th place, an even place, so it is \(80-5=75\).