Shortcut-3

To multiply a number by 11

Let’s take an example:

13423 * 11

Step – 1:

Take “0” on left and right hand sides:

Thus, we would get:

“0134230”

Step – 2:

Now, make pairs of 2 digits of the result “0134230”:

Thus,

Pairs are:

“01” ... “13” ... “34” ... “42” ... “23” ... “30”

Now add both the digits of all the pairs:

“01” = 0 + 1 = 1

“13” = 1 + 3 = 4

“34” = 3 + 4 = 7

“42” = 4 + 2 = 6

“23” = 2 + 3 = 5

“30” = 3 + 0 = 3

Hence,

Answer is:

147653

(It’s simple.)

Let’s take more examples.

123012 * 11

Step – 1:

Take “0” on left and right hand sides.

Thus, we get:

“01230120”

Step – 2:

Make 2 digit pairs of “01230120”

The pairs are:

“01” ... “12” ... “23” ...”30” ...  “01” ... “12” ... “20”

Now, simply add both the digits of pairs:

“01” = 1

“12” = 3

“23” = 5

“30” = 3

“01” = 1

“12” = 3

“20” = 2

Hence,

The answer is:

“1353132”

Let’s take one last example:

1020402 * 11

Step- 1:

Take “0” on left and right hand side:

We would get:

“010204020”

Step – 2:

Make pairs of 2 digits of “010204020”

Thus, the pairs are:

“01” ... “10” ... “02” ... “20” ... “04” ... “40” ... “02” ... “20”

Simply add the digits:

“01” = 1

“10” = 1

“02” = 2

“20” = 2

“04” = 4

“40” = 4

“02” = 2

“20” = 2

Hence, the answer is:

11224422





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