Activity Detail
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A Prime Investigation with 7, 11, and 13
 


Activity Overview

Students investigate the divisibility of 7, 11, and 13. They will also discover an interesting characteristic of six-digit multiples of 1001.

Before the Activity

  • See the attached PDF file for detailed instructions for this activity
  • Print pages 25 - 29 from the attached PDF file for your class

    		•

    		During the Activity

    		Distribute the pages to the class.

    Follow the Activity procedures:
  • Choose any three-digit number, repeat the three digits in the same order to form a six-digit number
  • Enter the number on the calculator and check if it is divisible by 7, 11, and 13
  • Repeat the activity with other three-digit numbers
  • Divide the six-digit number by the product of 7, 11, and 13
  • Observe that the result of the division is the original three-digit number
  • Multiply the product of 7, 11, and 13 with the three-digit number
  • Observe that the result of the multiplication is the original six-digit number
  • Write divisibility tests for 2, 3, and 5


    • Divisibility by 7
  • Take all but the last digit and form a number
  • Subtract twice the units digit from the number formed
  • Continue this process until the remainder is divisible by 7


    • Divisibility by 11
  • Take the sum of every other digit
  • Take the positive difference in the two sums and see if the answer is divisible by 11

    		After the Activity

    		Students will complete the Student Worksheet and analyze the results.

    Review student results:
  • As a class, discuss questions that appeared to be more challenging
  • Re-teach concepts as necessary

    		Other Downloads




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    Subject Area:
    Math : PreAlgebra : Number Sense and Operations
    Math : Middle Grades Math : Number Sense

    Author:
    Texas Instruments

    Level:
    5-8

    Activity Time:
    60 Minutes

    Device:
    TI-73 Explorer™

    Apps:
     

    Software:
     

    Accessories:
     

    Other:
    This is Activity 3 from the EXPLORATIONS Book:
    Discovering Mathematics with the TI-73: Activities for Grades 7 And 8



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