Find the least non-negative integer that must be added to 1057 so that the result is exactly divisible by 23. What value should be added?

Difficulty: Easy

Correct Answer: 1

Explanation:


Introduction / Context:
This problem tests modular arithmetic and divisibility. We want the smallest non-negative addition to 1057 that makes the sum a multiple of 23. Such questions appear frequently in aptitude tests to assess number sense and comfort with remainders.


Given Data / Assumptions:

  • Base number N = 1057.
  • Divisor d = 23.
  • We seek the least k >= 0 such that (N + k) is divisible by d.


Concept / Approach:
If r is the remainder when N is divided by d, then N = q*d + r. The smallest k that makes N + k a multiple of d is k = (d - r) when r != 0, and k = 0 when r = 0. We compute r using N mod d.


Step-by-Step Solution:

Compute a nearby multiple: 23 * 46 = 1058.Compare with 1057: 1057 = 1058 - 1, so remainder r = 22 (since 1057 mod 23 = 22).Find the least addition: k = 23 - r = 23 - 22 = 1.Check: 1057 + 1 = 1058, and 1058 / 23 = 46 (an integer).


Verification / Alternative check:
Direct division shows 23 * 46 = 1058; being one less means we must add 1 to reach the next multiple. This confirms k = 1.


Why Other Options Are Wrong:
2, 3, 4, and 6 overshoot the next multiple; adding any of them does not land exactly on a multiple of 23.


Common Pitfalls:
Confusing remainder 22 with the required addition; remember to add (23 - 22) and not 22 itself.


Final Answer:
1

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