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Thursday, December 29, 2011

Multiplication by 12 through a special method

Qs. 134 * 12=?

Write down the answer one figure at a time, from right to left as in any multiplication. Prefix a zero to the multiplicand so that it reads 0134.

0134

This method is exactly same as the previous method; here you double each number before adding the right neighbor.

134 * 12=?

Prefix a zero to the multiplicand so that it reads

0134 * 12=?

Double 4 and add the right neighbor (there is no right neighbor to 4 so add 0)

4*2=8+0= 8

Move left double 3 and add the right neighbor 4

3*2=6+4=10

Rest 0 and take 1 to the next number If in the process of addition, you get a two digit number, set down only the right digit and carry the left digit.

Double 1 and add the right neighbor 3 and the brought forward 1 from earlier

1*2=2+3+1=6

Double 0 and add the right neighbor 1

0*2=0+1=1

There fore 134 * 12= 1608

You can check it through conventional; multiplication.

Another example

13*12=?

013*12

6

5

1

= 156

You can check it through yours conventional method.

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