Multiplication of no's near by 1000

Trick for multiplication of 981 with 991.

991*981=?

SUBTRACT

991 from 1000

u will get "09"

similarly

SUBTRACT the other

u will get "19"

now multiply "09' and "19"
we get "171"


So The last three digits are "171"

Now Just subtract

"09" from 981
or
"19" from 991

In both the above cases u will get result as "972"
This gives the first 3 digits.


Therefore,

991*981=972171


Just try it other numbers......