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If 1 is added to each odd digit and 1 is subtracted from each even digit in the number 8436152, then what will be the difference between the last and the first digits from the left in the number thus formed?
4
3
6
5
6
Identify odd (1,3,5) and even (8,4,6,2) digits, apply the +1/-1 rule to the first and last, then find their absolute difference.
Identify odd (1,3,5) and even (8,4,6,2) digits, apply the +1/-1 rule to the first and last, then find their absolute difference.
Identify Target Digits
The original number is 8436152. The question requires the first digit from the left (8) and the last digit from the left (2).
Apply Transformation Rules
Rule: Add 1 to odd digits, subtract 1 from even digits. Both 8 and 2 are even, so subtract 1 from each. New first digit = 8 - 1 = 7. New last digit = 2 - 1 = 1.
Calculate Difference
The difference between the new last digit (1) and the new first digit (7) is 7 - 1 = 6.
A: 4 is incorrect as it does not result from 7-1. B: 3 is incorrect as it ignores the transformation logic. D: 5 is incorrect as it is a calculation error.
C is correct because the transformation of the first digit 8 (even) results in 7, and the transformation of the last digit 2 (even) results in 1, yielding a difference of 7 - 1 = 6.
Always verify if the digit being transformed is odd or even before applying the specific rule to avoid simple arithmetic slips.
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