Difficulty: Easy
Correct Answer: 101103
Explanation:
Introduction: Even in an approximation section, sometimes exact multiplication is expected. Use distributive expansion to keep the arithmetic simple and error-free, especially when one factor is just over a round hundred or thousand.
Given Data / Assumptions:
Concept / Approach: Expand 201 as (200 + 1) or 503 as (500 + 3). Apply the distributive property: (a + b)(c + d) = ac + ad + bc + bd. This avoids long multiplication and reduces mental load.
Step-by-Step Solution:
503 × 201 = 503 × (200 + 1) = 503 × 200 + 503 × 1 = 100600 + 503 = 101103Verification / Alternative check: Alternatively, (500 + 3)(200 + 1) = 500*200 + 500*1 + 3*200 + 3 = 100000 + 500 + 600 + 3 = 101103. Same result confirms correctness.
Why Other Options Are Wrong: 101100 is near but off by 3; 110000 and 100003 are far; 100500 is a mid-way distractor but incorrect.
Common Pitfalls: Dropping small cross terms (like 3*200 or 500*1). Keep every term from the expansion to avoid small but fatal errors.
Final Answer: 101103
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