the product's unit digit is the unit digit of 8*b. Therefore, the units digit should be the units digito of a multiple of 8
8*1=8 -> 8
8*2=16 -> 6
8*3 =24 -> 4
8*4 = 32 -> 2
8*5 =40 - > 0
8*6 = 48 -> 8 ..and the cycle repeats
so, we have 0,2,4,6,7 as the possible units digits and thus answer choice D is eliminated
4a8 * 60 + 4a8 * b = x
let's find the upper bound value i.e. the value the answer should certainly be less than
--> 500*70 = 3500 -> ans choice E is eliminated
now let's find the lower bound value
400*60 = 24000 -> ans choices A & B are eliminated
So, now we only have answer choice C as a possible answer and thefore this is the answer.
