Of course, here the answer can be written instantly as 63,since the answer can be taken from the arithmetic tables,which we have memorised.
Can you give instant answer for getting the product of 93 and 98 ?
No.You are not able to come out with an immediate answer as in the case of earlier sum.
Reason:
There are limitations to your memory or to arithmetic tables,which you have taken by heart.So,what is the way out now?
You will proceed through your traditional system as under:
93
98
___
744
837
___
9114
____
which will take atleast two or three minutes.
Now,I will give you a trick,by which you will be able to write the answer instantly.
Let us take now, 9*7(* represents multiplication operator).
ie. 9
7
__
__
Step 1:
Choose a number,which is common to both the given numbers.
This number is called the "Base Number".For our sum "10"
may be taken as Base Number. Ok?
Step 2:
Subtract the given numbers from the Base Number and write
the remainders after __ as under:
9__1 {here 9 is the given number,then dash
and then the remainder ie.after
subtracting 9 from the base number 10}
7__3
_____
_____