# SOLUTION: If J, K, and N are consecutive integers such that 0 < J < K < N and the unit's (ones) digit of the product JN is 9, what is the unit's digit of K ?

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 Click here to see ALL problems on Inequalities Question 55323: If J, K, and N are consecutive integers such that 0 < J < K < N and the unit's (ones) digit of the product JN is 9, what is the unit's digit of K ?Answer by Edwin McCravy(9719)   (Show Source): You can put this solution on YOUR website!```If J, K, and N are consecutive integers such that 0 < J < K < N and the unit's (one's) digit of the product JN is 9, what is the unit's digit of K Since JN ends in 9, then either 1. J and N both end in 3 Or 2. One of J, N ends in 9 and the other ends in 1 They can't both end in 3 because N is 2 more than J, and if one of them ended in 3 the other would either have to end in either 1 or 5. So case 1 is out. So case 2 is the only possibility. J can't end in 1 because since N=J+2 that would make N end in 3, not 9 So J must end in 9 and N, being 2 more than J, must end in 1. So K, being 1 less than a number ending in 1, and 1 more than a number ending in 9, must end in 0. That's the answer, 0, since the unit's digit is the last digit. Edwin```