Let n be a positive integer. If a = 414n + 12 , what is the remainder when a is divided by 9?
414 is divisible by 9
=> 414n is divisible by 9
=> 414n + 9 is divisible by 9
414n + 12 = (414n + 9) + 3
414n + 12 is 3 more than a multiple of 9. The required remainder is 3.