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7.E: Exercises

  • Page ID
    7611
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    Exercise \(\PageIndex{1}\)

    Convert \(101101101_2\) to base \(10\).

    Answer

    TBD.

    Exercise \(\PageIndex{2}\)

    The tripletown number system use only numbers which are \(1\) more than some multiples of \(3\).

    1. Construct a \(5\times5\) tripletown number system of multiplication table with the numbers \(1,4,7,10\) and \(13.\)
    2. Find the smallest ten prime numbers in the tripletown number system.
    3. Find a number with two different tripletown number system prime factorizations.
    4. Does the Prime divisibility Theorem hold for the tripletown number system? Explain.

    Exercise \(\PageIndex{3}\)

    The Quadritown number system use only numbers which are \(1\) more than some multiples of \(4\).

    1. Construct a \(5\times5\) Quadritown number system of multiplication table with the numbers \(1,5,9,13\) and \(17.\)
    2. Find the smallest ten prime numbers in the Quadritown number system.
    3. Find a number with two different Quadritown number system prime factorizations.
    4. Does the Prime divisibility Theorem hold for the Quadritown number system? Explain.
    Answer

     

    X

    1

    5

    9

    13

    17

    1

    1

    5

    9

    13

    17

    5

    5

    25

    45

    65

    85

    9

    9

    45

    81

    117

    153

    13

    13

    65

    117

    169

    221

    17

    17

    85

    153

    221

    289

     

    Answer

    5, 9, 13, 17, 21, 29, 33, 37, 41, 49

    3. Find a number with two different Quadritown prime factorizations.

    A solution: (found by trial and error)

    Examples

    Product

    Prime Factorization #1

    Prime Factorization

    #2

    441

    (21)(21)

    (9)(49)

    1089

    (33)(33)

    (9)(121)

    2205

    (5)(21)(21)

    (5)(9)(49)

    3249

    (57)(57)

    (9)(361)

     

    Prime divisibility is defined as follows:

    Let p be a prime and let a and b be integers. If p ∣(ab)then p∣a or p∣b.

    Thus, prime divisibility does not hold for the Quadritown number system since 21 | 441and 21 | (9)(49), but 21 ∤ 9nor does 21 ∤ 49. Note, this argument could be modified for each of the examples identified in part c.

     


    This page titled 7.E: Exercises is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Pamini Thangarajah.

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