Refer to the following series and answer the question. Count from left to…
2026
Refer to the following series and answer the question. Count from left to right only. All numbers are single-digit numbers.
(Left) 8 2 1 3 7 9 5 1 4 2 5 8 4 1 3 7 4 2 9 4 5 9 2 1 3 4 5 6 8 (Right)
How many odd digits are immediately preceded by an odd digit and immediately followed by an even digit?
Answer: D. More than three — ConceptFor a local pattern in a number series, test each eligible middle position together with its immediate left and right neighbours. Here the required…
- A.
Three
- B.
Two
- C.
One
- D.
More than three
Attempted by 56 students.
Show answer & explanation
Correct answer: D
Concept
For a local pattern in a number series, test each eligible middle position together with its immediate left and right neighbours.
Here the required parity pattern is odd–odd–even: the middle digit must be odd, its predecessor must be odd, and its successor must be even. Count each qualifying middle position once.
Application
Scan the series from left to right and retain only consecutive triples with the odd–odd–even pattern:
5, 1, 4: the middle digit 1 has an odd predecessor 5 and an even successor 4.
3, 7, 4: the middle digit 7 has an odd predecessor 3 and an even successor 4.
5, 9, 2: the middle digit 9 has an odd predecessor 5 and an even successor 2.
1, 3, 4: the middle digit 3 has an odd predecessor 1 and an even successor 4.
Qualifying triple | Counted middle digit |
|---|---|
5, 1, 4 | 1 |
3, 7, 4 | 7 |
5, 9, 2 | 9 |
1, 3, 4 | 3 |
Cross-check and contrast
Marking the four middle positions gives 1, 7, 9, and 3. No endpoint is counted because an endpoint lacks one neighbour, and no other odd middle digit has both required neighbours.
The counts one, two, and three are each below the four qualifying middle positions found in the scan.
The category more than three includes the derived count of four.
Therefore the count is 4, which is more than three.