Difficulty: Medium
Correct Answer: 2070
Explanation:
Introduction / Context:
This problem combines decimal subtraction with a division by a small decimal ratio, testing careful manipulation of place values and reciprocals.
Given Data / Assumptions:
Concept / Approach:
First simplify the numerator. Then recognize that dividing by a small number is equivalent to multiplying by its reciprocal; compute the denominator exactly to avoid compounding decimal errors.
Step-by-Step Solution:
Verification / Alternative check:
Rewrite the compound fraction: (0.23 − 0.023) * (23 / 0.0023) = 0.207 * 10000 = 2070, the same result.
Why Other Options Are Wrong:
0.207 and 0.0207 ignore the denominator’s effect. 207 under-multiplies by a factor of 10. 20.7 is still short by two orders of magnitude.
Common Pitfalls:
Miscomputing 0.0023 / 23 or moving the decimal point incorrectly when dividing by a ten-thousandth.
Final Answer:
2070
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