multiply any no with 9,99,999,9999 & so on easily

example1 - 18 * 99
step 1- put 2 zeros after 18 (as we have to mul it by 99, and 99 has 2 digits)

it becomes 1800 now

step 2- now subtract 18 from 1800
ans is 1782

example2- 482*9999

step1- put 4 zeros after 482 (as we have to mul 482 by 9999, and 9999 has 4 digits)

it becomes 4820000

step 2- subtract 482 from 4820000

ans is 4819518