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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This was really interesting. I liked it.
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.
gr8888888888888888888888888888888888ttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttt
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.
How to do the same for 7895 x 11?
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
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.