Approximation using complements: Compute 98743 ÷ 198 and express it as 800 − ?, then determine the missing value (closest option).

Difficulty: Easy

Correct Answer: 300

Explanation:


Introduction / Context:
This problem reframes a division as a complement-to-800 calculation. By first approximating or computing 98743 ÷ 198, we can subtract the quotient from 800 to obtain the required missing amount. This is a common trick to make mental computation easier when the target figure is a round number like 800.


Given Data / Assumptions:

  • N = 98743
  • D = 198
  • We want 800 − (N ÷ D)


Concept / Approach:
Compute or estimate the quotient Q = N / D. Then the answer is 800 − Q. Because 198 is very close to 200, we can use 98743/200 as a quick ballpark and refine slightly since dividing by 198 gives a slightly larger quotient than dividing by 200.


Step-by-Step Solution:

Rough: 98743 ÷ 200 ≈ 493.7Since the real divisor (198) is smaller, the real quotient is slightly bigger, ≈ 499Exact computation gives about 498.70Therefore 800 − 498.70 ≈ 301.3


Verification / Alternative check:
Use back-multiplication: if the answer were exactly 300, then the quotient would be 800 − 300 = 500. That is very close to 498.7, and 300 is the nearest given option to 301.3.


Why Other Options Are Wrong:

  • 200: Implies quotient 600, too high.
  • 250: Implies quotient 550, too high.
  • 350: Implies quotient 450, too low.
  • 275: Implies quotient 525, still too high.


Common Pitfalls:
Forgetting that a smaller divisor (198 vs. 200) increases the quotient; also, rounding too coarsely can push the complement far away from the true value.


Final Answer:
300

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