How many even numbers are there in the following series of numbers, each of which is preceded by an odd number and followed by an odd number?
5 3 4 8 9 7 1 6 5 3 2 9 8 7 3 5
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Three
Look at every even number in the series and check its two neighbours: the number just before it and the number just after it must both be odd.
5 3 4 8 9 7 1 6 5 3 2 9 8 7 3 5
4 (3rd): before it 3 (odd), but after it 8, which is even — does not count
8 (4th): before it 4, which is even — does not count
6 (8th): before it 1 (odd), after it 5 (odd) — counts
2 (11th): before it 3 (odd), after it 9 (odd) — counts
8 (13th): before it 9 (odd), after it 7 (odd) — counts
So three even numbers (6, 2 and the second 8) have an odd number on both sides.