Divisible by 11

An Advanced Mathematics Lesson Starter Of The Day

Can you prove that a three digit number whose first and third digits add up to the value of the second digit must be divisible by eleven?

The number eleven

Share

Topics: Starter

    How did you use this starter? Can you suggest how teachers could present or develop this resource? Do you have any comments? It is always useful to receive feedback and helps make this free resource even more useful for Maths teachers anywhere in the world.
    Click here to enter your comments.

    If you don't have the time to provide feedback we'd really appreciate it if you could give this page a score! We are constantly improving and adding to these starters so it would be really helpful to know which ones are most useful. Simply click on a button below:

    Excellent, I would like to see more like this
    Good, achieved the results I required
    Satisfactory
    Didn't really capture the interest of the students
    Not for me! I wouldn't use this type of activity.

    This starter has scored a mean of 2.0 out of 5 based on 1 votes.


    Previous Day | This starter is for | Next Day

     

    Answer

    Let the first digit be x and the third digit be y.

    The three digit number has a value of 100x + 10(x+y) + y

    = 110x + 11y

    = 11(10x + y)

    As this has a factor of 11 it must be divisible by 11

    More Mathematics Lesson Starters

    How did you use this starter? Can you suggest how teachers could present or develop this resource? Do you have any comments? It is always useful to receive feedback and helps make this free resource even more useful for Maths teachers anywhere in the world. Click here to enter your comments.



    Your access to the majority of the Transum resources continues to be free but you can help support the continued growth of the website by doing your Amazon shopping using the links on this page. Below is an Amazon search box and some items chosen and recommended by Transum Mathematics to get you started.

     

    Puzzle Master Banner
    Numbers and the Making of Us

    Numbers and the Making of Us

    I initially heard this book described on the Grammar Girl podcast and immediately went to find out more about it. I now have it on my Christmas present wish list and am looking forward to receiving a copy (hint!).

    "Caleb Everett provides a fascinating account of the development of human numeracy, from innate abilities to the complexities of agricultural and trading societies, all viewed against the general background of human cultural evolution. He successfully draws together insights from linguistics, cognitive psychology, anthropology, and archaeology in a way that is accessible to the general reader as well as to specialists." more...


    Apple

    ©1997-2019 WWW.TRANSUM.ORG