In this lesson, you will learn two different methods to test if a number is divisible by 11, regardless of its size. The first method involves adding the outside digits and subtracting the middle one, while the second method requires crossing off the last digit and subtracting the remaining digits. You will also learn a method to test if a number is divisible by 13, which involves multiplying the last digit by 4 and adding it to the remaining digits. These tricks are useful for quickly determining the divisibility of large numbers.
Goes over two divisibility tests for 11 and also the one for 13.
More free YouTube videos by Julie Harland are organized at http://yourmathgal.com