Multiply any number with 11 or 12 or 19 in just 5 seconds!

You need not scratch your head, if you don't know 11 table. You can do this multiplication in 5 seconds, if you know simple additions. Surprised! yes, we would get the product of the numbers using addition.

Note that we would add the digits present in the number from right to left and also, imagine a 0 before and after the number i.e., if the number is 123 then consider it as 01230.

Let us calculate 789 x 11
Step 1: Consider a 0 before and after the number. ie, 07890
Step 2: Now for this number, add last two digits from right, 9 + 0 = 9. Therefore 789 x 11 = ___9
Step 3: Add the next two digits, here 8+9 =17. Write the last digit - 7 of the sum and take the carry - 1 to next step. Therefore 789 x 11 = __79
Step 4: Add the next two digits and the carry in step2, here (7 + 8 = 15) + 1 = 16. Write the last digit - 6 of the sum and take the carry - 1 to next step. Therefore 789 x 11 = _679
Step 5: Add the next digit and the carry in step 3, here 0 + 7 + 1 = 8. Write the sum against the result.
Therefore 789 x 11 = 8679

Now let us try calculating 12345 x 11
Step 1 : 0123450
Step 2 : 12345 x 11 = _____5 (5 + 0 = 5)
Step 3 : 12345 x 11 = ____95 (4 + 5 = 9)
Step 4 : 12345 x 11 = ___795 (3 + 4 = 7)
Step 5 : 12345 x 11 = __5795 (2 + 3 = 5)
Step 6 : 12345 x 11 = _35795 (1 + 2 = 3)
Step 7 : 12345 x 11 = 135795 (0 + 1 + no carry = 1)
Therefore 12345 x 11 = 135795

Let us try 4567 x 11
Step 1: 045670
Step 2: 4567 x 11 = ____7 (7 + 0 = 7)
Step 3: 4567 x 11 = ___37 (6 + 7 = 13, 3 with carry 1)
Step 4: 4567 x 11 = __237 (5 + 6 = 11 + 1 = 12, 2 with carry 1)
Step 5: 4567 x 11 = _0237 (4 + 5 = 9 + 1 = 10, 0 with carry 1)
Step 6: 4567 x 11 = 50237 (0 + 4 + 1 = 5)
Therefore 4567 x 11 = 50237

Simple right. In Vedic Mathematics the above method is called as Adding to the Neighbor.

Easy right...and if I am not wrong you must be thinking it would be so nice if so some method is present for multiplying numbers with 12, 13, 14....19. So that we need not by heart the tables.

We can extend the above method with slight modification. All you need to do is that when multiplying the number with 12, double the digit before adding to the neighbor. For 13, just triple the digit before adding to the neighbor. For 14 its 4 times and so on you can do for all the numbers till 19. Lets try few examples .

Calculate 7654 x 12
Step 0: 076540
Step 1: 7654 x 12 = ____8 (4 x 2 = 8 + 0 = 8)
Step 2: 7654 x 12 = ___48 (5 x 2 = 10 + 4 = 14, 4 with carry 1)
Step 3: 7654 x 12 = __848 (6 x 2 = 12 + 5 = 17 + 1 = 18, 8 with carry 1)
Step 4: 7654 x 12 = _1848 (7 x 2 = 14 + 6 = 20 + 1 = 21, 1 with carry 2)
Step 5: 7654 x 12 = 91848 (0 x 2 = 0 + 7 + 2 = 9)
Therefore 7654 x 12 = 91848

Calculate 12345 x 13
Step 0: 0123450
Step 1: 12345 x 13 = _____5 (5 x 3 = 15 + 0 = 15, 5 with carry 1)
Step 2: 12345 x 13 = ____85 (4 x 3 = 12 + 5 = 17 + 1 = 18, 8 with carry 1)
Step 3: 12345 x 13 = ___485 (3 x 3 = 9 + 4 = 13 + 1 = 14, 4 with carry 1)
Step 4: 12345 x 13 = __0485 (2 x 3 = 6 + 3 = 9 + 1 = 10, 0 with carry 1)
Step 5: 12345 x 13 = _60485 (1 x 3 = 3 + 2 = 5 + 1 = 6, no carry)
Step 6: 12345 x 13 = 160485 (0 x 3 = 0 + 1 = 1)
Therefore 12345 x 13 = 160485

You can try multiplying the numbers with 14, 15, 16, 17, 18 and 19 and check the answers with either standard method or calculators.
Hope this simple method of multiplying has helped you in speeding up your calculations. If you have any queries or if you have any other simpler method to solve, then do let us know.