What is the remainder when (32540 x 42400 x 3233) + 222 is divided by 13?
32540 using the divisibility test for 13 ( triplets at odd- triplets at even places ) can be written as
540-32= 508. 508 when divided by 13 can be represented as 13k + 1 (i.e. when the number is divided by 13, the remainder is 1)
Similarly
42400= 400-42= 358 = 13k + 7
3233= 233-3=230= 13k + 9
(13k + 1)( 13k + 7)(13k + 9) will give the non-divisible part as (9x7x1) = 63
therefore 63+222= remainder of 285 when divided by 13= -1 or 12