You must have studied Multiplication earlier . By now, you'll be thinking that you should know the tables of numbers upto 10, using which you can multiply greater numbers. Is it necessary that you need to memorise tables upto 10? You can do with 5.Take the case of 9 x 7, which you know is 63.

Write the two numbers, one below the other, on the left hand side. Subtract 10 from each of them, and write the difference on the right hand side as follows 

	9	-1
      7	    -3
Now multiply the numbers on the right hand side (-1 and -3 ) to get 3 as the last digit of the product. Add the two numbers on the left (9 and 7) to get 16 and subtract the nearest power of 10 (10 in this case) from it to get the next digit (to get 6). So

9 -1

7 -3

--------

6 3

This method is called 'Nikhilam'. In the above case, the numbers are close to 10. 10 is referred to as the base. Another way of obtaining the left hand side of the product is by cross-addition. In the above case 6 can be obtained by cross addition of 9 and -3 or 7 and -1.

Let's try some more examples

  • 8 x 7
  • 9 x 9

Now, you may wonder why do we need special methods for multiplying such small numbers? What about big numbers? The same method can be applied to multiply numbers, which are near to any power of 10. Thus the base can be any power of 10.

 

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