.
Now we shall discuss another Simple and Useful method for
Multiplication. In this method we take a base (according to the given
numbers) and do the multiplication according to that base. Assume that
you have to multiply 97 with 92. The power of 10 to which these two
numbers are close is 100. We call this 100 as the base. Now write these two numbers with the difference from the base.
97 ------> -3 (because 97 is obtained as 100 - 3)
92 ------> -8 (because 92 is obtained as 100 -8)
Then take the sum of the two numbers (including their signs) along
either one of the two diagonals (see, it will be same for both cases).
Have a look at the above example,