Multiplication of a number close to hundred :- 

The number which is close to hundred can be find within a seconds with the following steps :-

99*98=  

-1    -2 

Step 1 ) 99-100= -1 

Step 2) 98-100 = -2 

Step 3) -1-2= -3 

Step 4) 100 + (-3) = 97 

Step 5) -1*-2=02

Step 6) combining Step 4 and Step 5 = 9702

Hope this is helpful