Question

    Find the number of zeros at the end of

    78!.
    A 16 Correct Answer Incorrect Answer
    B 20 Correct Answer Incorrect Answer
    C 18 Correct Answer Incorrect Answer
    D 12 Correct Answer Incorrect Answer

    Solution

    Number of zeros will depend on the number of 10s. Since, 10 = 5 X 2, number of 10s will depend on number of 5s. {Since, number of 2s will always be more} So, number of fives at the end of 78! = [78/5] + [78/25] {Where [] is greatest integer} = 15 + 3 = 18

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