Mental Math Shortcut Multiplying by 11

How do we multiply by eleven easily?

First we will try this by writing the answer backwards.

So, when always multiplying a large number by 11, the last number will always be the last number of the sum we are multiplying.

Let me explain.

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7 Responses to “Mental Math Shortcut Multiplying by 11”

  1. This was really interesting. I liked it.

  2. Another way of doing it will be
    1] 76 X 11
    write the digit with space in between like
    7 6
    now add both of them 7+6=13
    write 13 in between them
    7 13 6
    now carry 1 from 13 to 7 and add it.you get
    836 the answer.
    2] 176 x 11
    17 6
    17+6=23
    17 23 6
    17+2 = 19
    so we get
    1936 the answer.

  3. gr8888888888888888888888888888888888ttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttt

  4. If you would like to see an animation of this contact me. Remember a picture is worth a thousand words, a movie maybe a google away.

  5. How to do the same for 7895 x 11?

  6. For getting the answer of 7895*11 :
    The steps are as follows

    1) Divide 7895 in 2 partitions as 789 5
    2) 789+ 5 = 794
    3) 79 is carry which is to be added in 789 to give 789 + 79 =868 Thus we get the first part of answer as 868, second part 4, third part 5
    Therefore the final answer is 86845

  7. Both the methods provided above are great.
    But I feel the traditional way in this particular case(Multiplying by 11) as easy.
    e.g. 1279 x 11

    Add [number appeneded with 0] to [same number]
    12790 + 1279 = 14069

    For me, it is faster.

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