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    Question

    Consider a number of the form '49678a' which is divisible

    by 6 but not divisible by 5. Find the value of (a × 2 + 3).
    A 12 Correct Answer Incorrect Answer
    B 18 Correct Answer Incorrect Answer
    C 7 Correct Answer Incorrect Answer
    D 10 Correct Answer Incorrect Answer

    Solution

    ATQ,

    Divisibility by 6 ⇒ divisible by both 2 and 3.

    Sum of digits = 4 + 9 + 6 + 7 + 8 + a = 34 + a

    To be divisible by 3: (34 + a) must be divisible by 3

    Also, a must be even (for divisibility by 2), and not 0 or 5.

    Even options: 0, 2, 4, 6, 8

    Try a = 2 → 34 + 2 = 36 ✅

    So, a = 2

    (2×a + 3) = 2×2 + 3 = 7

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