Explanation
1. Understanding the Condition:
We need to find the digit 5 such that:
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It is immediately followed by 4 (e.g., 54).
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It is NOT immediately preceded by 6 (e.g., should not be 654).
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Formula: [Not 6]→5→4
2. Analyzing the Series:
Let's scan the series for every occurrence of 5 and check the digits around it:
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456: Followed by 6. (Incorrect)
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656: Followed by 6. (Incorrect)
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455: Followed by 5. (Incorrect)
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455: Followed by 4. Preceded by 5. (Correct: 554 sequence starts here)
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455: Followed by 5. (Incorrect)
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455: Followed by 6. (Incorrect)
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654: Followed by 4, but preceded by 6. (Incorrect)
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456: Followed by 6. (Incorrect)
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456: Followed by 6. (Incorrect)
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54: Followed by 4. Preceded by 6 (from previous 456). (Incorrect)
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54: (End of series) Followed by 4. Preceded by 4. (Correct: 454)
3. Counting the Valid Occurrences:
Let's look at the raw string of numbers again:
4 5 6 6 5 6 4 5 5 4 5 5 6 5 4 4 5 6 4 5 6 5 4 5 4
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...5 5 4... (The 5 is followed by 4 and preceded by 5).
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...4 5 4... (The 5 is followed by 4 and preceded by 4).
There are exactly two such 5s that meet the criteria.
Correct Option: (d) Two
