## Math: combinations: a question from a text

The tutor offers a solution to a textbook question about counting. On page 47 of my text Discrete and Combinatorial Mathematics (Grimaldi) is a question: If you want to select three distinct letters from the alphabet , arranged in alphabetical …

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## Math: the pigeonhole principle: another example

Tutoring high school math, the pigeonhole principle might not come up very often.  Because of its applications to everyday life, the tutor often thinks of it. Back in my May 23 post, I introduced the pigeonhole prinicple. I pointed out …

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## Math: the pigeonhole principle

Tutoring math, you might see this topic from a university student.  The math tutor offers it as a point of interest. The pigeonhole principle is used to solve counting problems.  A simple example: In a ten day stretch, how many …

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## Math: counting: multiply or add

Tutoring math 12, you may discuss counting problems.  The tutor offers a quick guide for when to multiply vs when to add. One question you’re sometimes asked about counting is when you multiply, vs when you add.  The answer is …

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## Math: A counting problem

Tutoring math 12 and some university courses, you get asked about counting. The tutor opens the discussion with a couple of examples. Questions that ask, “How many ways can people be lined up for a photograph” or “how many five-card …