Find the number of digits in 8^57. (Given log10 2 = 0.3010)
Aptitude
Logarithm
Difficulty: Easy
Choose an option
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A52
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B50
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C51
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D53
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ENone of these
Answer
Correct Answer: 52
Explanation
Introduction / Context:We again use the digit-count identity: digits = floor(log10 N) + 1. Express 8^57 as a power of 2 to leverage the provided log10 2 value.
Given Data / Assumptions:
- N = 8^57 = (2^3)^57 = 2^171.
- log10 2 = 0.3010.
Concept / Approach:
- Compute log10(2^171) = 171 * 0.3010.
- Apply digits = floor(log10 N) + 1.
Step-by-Step Solution:
log10 N = 171 * 0.3010 = 51.471Digits = floor(51.471) + 1 = 51 + 1 = 52Verification / Alternative check:Since 10^51 < N < 10^52 and it is not an exact power of 10, the digit count must be 52.
Why Other Options Are Wrong:
- 50, 51, 53 result from rounding errors or dropping the +1.
Common Pitfalls:
- Using 0.3 instead of 0.3010 gives 51.3 and still yields 52 digits, but coarser approximations can mislead if rounding is mishandled.
Final Answer:52