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  • Perplex
    IB Math AAHL
    /
    Counting & Binomials
    /

    Problem Bank

    [Maximum mark: 9]

    A ​6​-character code is assembled from the letters ​A,B,C,D​ and digits ​0​-​9.

    1. Find the total number of possible codes if

      1. the letters and digits can be reused,

        [1]

        To earn a crown, get your answer ready before you reveal the options!

      2. the letters and digits cannot be reused.

        [1]

    Now it is given that all ​4​ letters are used once and digits cannot be reused, and that no ​3​ letters can be consecutive.

    1. Find the number of possible codes under these conditions.

      [7]

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