Multiplication of Numbers Close to 100,1000 etc

Multiplication of Numbers Close to 100,1000 etc.
 
By Using Shortcuts we can calculate multiplication of numbers close to 100,1000 etc. within 10 seconds.

   98
X 93
---------
9114
---------
Explanation:

Step 1: Here the base value is 100 because of 98,93 are the close to 100
Step 2: Consider difference of numbers from base value(100) i.e. -2, -7  (Consider Sign also either it is Positive or Negative)
Note: if the numbers are close to 1000 base value is 1000

   98    (100-98 =2)  +2                 98   +2
X 93    (100-93 =7)  +7             X  93   +7
-------------------------------              ----------------
Here consider Cross Difference i.e  98 -7 =91,  93-2  = 91 then add Two Zero after 91  i.e.  9100 because of base value is 100 (91*100 = 9100)
now the tentative answer is 9100 (not over)
then Multiply    +2,+7,  i.e. +14
+14 is add to 9100

9100
     +  +14
    ----------------
Required Answer is 9114
                                       ---------

    102
      X  98
    -------------

Here Base value is 100


   102    (100-102 = -2)   -2
X  98     (100-98  = +2)  +2
---------------------------------------

102 -2 =100
 98-(-2)=100

Here Cross difference is 100 then add Two Zero after 100 i.e.  10000 because of base value is 100
Answer is 10000  +   -2  *  +2  = -4
Add -4 is to    10000
                 X         -4
       -----------
Answer:         9996
          ----------