Quick Multiplication by 11



Step 1: Assume that there are two invisible 0 (zeroes), one in front and one behind the number to be multiplied with 11

say if the number is 234, assume it to be  0 2 3 4 0

Step 2. Start from the right, add the two adjacent digits and keep on moving left

02340

Add the last zero to the digit in the ones column (4), and write the answer below the ones column. Then add 4 with digit on the left i.e. 3. Next add 3 with 2. Next 2 with 0.

0+4 = 4

4+3 = 7

3+2 = 5

2+0 = 2

So answer is 2574

Similarly,

36 x 11 = 0+3   |   3+6   | 6+0  = 396

74 x 11 =0+ 7 |  7+4 |  4+0 =  7  | 11 |  4 = 814   (1 of 11 is carried over and added to next digit, so 7+1 = 8 )
6349 x 11 = (0+6)  |  (6+3)   |   (3+4)   |   (4+9)  |   9+0 =  69839

This method works for all the number, no matter how long or short, times 11. Just try it yourself and get amazed at the simplicity of the concept.

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