Difficulty: Easy
Correct Answer: 70.464
Explanation:
Introduction / Context:
This problem checks decimal square-root fluency. Recognizing that decimal shifts in the radicand correspond to dividing or multiplying the square root by 10 helps compute quickly without a calculator.
Given Data / Assumptions:
√4096 = 64 is provided.
Concept / Approach:
Note that 40.96 = 4096 / 100, so √40.96 = √4096 / 10 = 6.4. Also, 0.004096 = 4096 / 1,000,000, so √0.004096 = √4096 / 1000 = 0.064.
Step-by-Step Solution:
Verification / Alternative check:
Square 6.4 to confirm 40.96 and 0.064 to confirm 0.004096: 6.4^2 = 40.96; 0.064^2 = 0.004096.
Why Other Options Are Wrong:
70.4 and 71.4 ignore the last term or round incorrectly; 71.104 is an over-add; 69.464 undercounts.
Common Pitfalls:
Mistaking decimal place movements when square-rooting decimal numbers; remember √(a/100) = √a / 10 and √(a/10^6) = √a / 1000.
Final Answer:
70.464
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