(i) The least number that should be subtracted from a so that b divides the difference exactly

Find the least number which should be subtracted from 9999 so that the difference is exactly divisible by 16 ?

(ii) The least number that should be added to a so that b divides the sum exactly =b-r.

What number should be subtracted from -3/5 to get-2?

What is the least positive integer that should be subtracted form 2750 so that the difference is a perfect cube?

What number should be subtracted from (-5)/(7) to get -1?