Compute the exact product: 503 × 201 = ?

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:

  • Compute 503 × 201 exactly.
  • Both numbers are close to “round” decompositions.


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 = 101103


Verification / 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

Discussion & Comments

No comments yet. Be the first to comment!
Join Discussion