UPSC Prelims 2020·CSAT·Logical Reasoning·Series and Sequences

Consider the following sequence of numbers: 5 1 4 7 3 9 8 5 7 2 6 3 1 5 8 63852243496 How many odd numbers are followed by the odd number in the above sequence?

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Last updated 23 May 2026, 3:31 pm IST
  1. A5
  2. B6Correct
  3. C7
  4. D8

Explanation

To solve this, we need to identify instances where an odd number is immediately followed by another odd number in the given sequence. The sequence is: 5 1 4 7 3 9 8 5 7 2 6 3 1 5 8 6 3 8 5 2 2 4 3 4 9 6 Let's scan the sequence for pairs of (Odd, Odd): 1. (5, 1) - Yes 2. (7, 3) - Yes 3. (3, 9) - Yes 4. (5, 7) - Yes 5. (3, 1) - Yes 6. (1, 5) - Yes Counting these pairs, we find there are 6 such instances. Therefore, 6 odd numbers are followed by an odd number in the given sequence. The final answer is B) 6.
Logical Reasoning: Consider the following sequence of numbers: 5 1 4 7 3 9 8 5 7 2 6 3 1 5 8 63852243496 How many odd numbers are followed

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