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    IB Math AASL
    /
    Counting & Binomials
    /

    Video

    Video Reviews

    Watch comprehensive video reviews for most units, designed for final exam preparation. Each video includes integrated problems you can solve alongside detailed solutions.

    Not your average video:

    Interactive Problems: Solve problems alongside the video with step-by-step guidance and detailed solutions.

    Exam Preparation: Complete unit reviews designed for final exam preparation with all key concepts covered systematically.

    Expert Teaching: High-quality instruction from Perplex co-founder James Mullen with clear explanations, worked examples, and exam tips.

    Not your average video:

    Interactive Problems: Solve problems alongside the video with step-by-step guidance and detailed solutions.

    Exam Preparation: Complete unit reviews designed for final exam preparation with all key concepts covered systematically.

    Expert Teaching: High-quality instruction from Perplex co-founder James Mullen with clear explanations, worked examples, and exam tips.

    Counting & Binomials

    Video Reviews

    Watch comprehensive video reviews for Counting & Binomials, designed for final exam preparation. Each video includes integrated problems you can solve alongside detailed solutions.

    Not your average video:

    Interactive Problems: Solve problems alongside the video with step-by-step guidance and detailed solutions.

    Exam Preparation: Complete unit reviews designed for final exam preparation with all key concepts covered systematically.

    Expert Teaching: High-quality instruction from Perplex co-founder James Mullen with clear explanations, worked examples, and exam tips.

    Not your average video:

    Interactive Problems: Solve problems alongside the video with step-by-step guidance and detailed solutions.

    Exam Preparation: Complete unit reviews designed for final exam preparation with all key concepts covered systematically.

    Expert Teaching: High-quality instruction from Perplex co-founder James Mullen with clear explanations, worked examples, and exam tips.

    SL TheoryBinomial ProblemsCounting (HL)

    The video will automatically pause when it reaches a problem.

    Factorials

    SL AA 1.9

    Factorials are shortcut used to express decreasing products of integers such as

    5⋅4⋅3⋅2⋅1=5!


    The definition is

    n!=n×(n−1)×⋯×2×1🚫


    Alternatively, n! can be defined recursively by:

    0!=1
    n!=n⋅(n−1)!

    This second definition is helpful when simplifying fractions of factorials:

    k!n!​=k!n(n−1)⋯(k+1)⋅k!​=n(n−1)⋯(k+1)🚫


    Example

    Find 8!11!​.

    8!11!​=8!11×10×9×8!​=990

    Factorials

    SL AA 1.9

    Factorials are shortcut used to express decreasing products of integers such as

    5⋅4⋅3⋅2⋅1=5!


    The definition is

    n!=n×(n−1)×⋯×2×1🚫


    Alternatively, n! can be defined recursively by:

    0!=1
    n!=n⋅(n−1)!

    This second definition is helpful when simplifying fractions of factorials:

    k!n!​=k!n(n−1)⋯(k+1)⋅k!​=n(n−1)⋯(k+1)🚫


    Example

    Find 8!11!​.

    8!11!​=8!11×10×9×8!​=990
    SL TheoryBinomial ProblemsCounting (HL)