Shortcuts for Mathematical operations (Multiplication)

1. Multiplication: is nothing but repetitive addition.



 87 x 93  =?



Traditionally we know how to deal with this.



87 x 93

------------

        261

      783

--------------

    8091

--------------



this is done in another way is



87 is  13 difference to 100

93 is  07 difference to 100



87 - 13

93 - 07 ( apply cross subtraction here)



i.e 87-07 = 80

    93- 13 =80

  and multiply the differences 07 x 13 = 91



so the answer is 8091



2. 76 x 82 =?



 76 is 24 diff to 100

 82 is 18 diff to 100



so as per apply cross subtraction 76-18 and 82-24 is 58



and multiply the difference 24 x 18 = 432 here take 32 and 4 as carry  it is added to the 58



so the answer is (58+4)32 = 6232