document.write( "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 ? \n" ); document.write( "
Algebra.Com's Answer #37544 by Edwin McCravy(20056)\"\" \"About 
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If J, K, and N are consecutive integers such that 0 < J < K < N \r\n" );
document.write( "and the unit's (one's) digit of the product JN is 9, what is the unit's\r\n" );
document.write( "digit of K \r\n" );
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document.write( "Since JN ends in 9, then either\r\n" );
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document.write( "1. J and N both end in 3\r\n" );
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document.write( "Or\r\n" );
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document.write( "2. One of J, N ends in 9 and the other ends in 1\r\n" );
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document.write( "They can't both end in 3 because N is 2 more than J, and if\r\n" );
document.write( "one of them ended in 3 the other would either have to end \r\n" );
document.write( "in either 1 or 5.  So case 1 is out.\r\n" );
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document.write( "So case 2 is the only possibility. \r\n" );
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document.write( "J can't end in 1 because since N=J+2 that would make N end\r\n" );
document.write( "in 3, not 9\r\n" );
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document.write( "So J must end in 9 and N, being 2 more than J, must end in 1.\r\n" );
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document.write( "So K, being 1 less than a number ending in 1, and 1 more than\r\n" );
document.write( "a number ending in 9, must end in 0.\r\n" );
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document.write( "That's the answer, 0, since the unit's digit is the last digit.\r\n" );
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document.write( "Edwin
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