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 5Divisibility by 7Take 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 7Divisibility by 11
Take the sum of every other digitTake 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