document.write( "Question 1207584: Let $N$ be a positive integer. The number $N$ has three digits when expressed in base $7$. When the number $N$ is expressed in base $12$, it has the same three digits, in reverse order. What is $N$? (Express your answer in decimal.) \n" ); document.write( "
Algebra.Com's Answer #845542 by greenestamps(13200)\"\" \"About 
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\n" ); document.write( "It appears that there is no solution.

\n" ); document.write( "My work is shown below; perhaps another tutor will find an error in my work and find a solution to the problem.

\n" ); document.write( "N = ABC base 12:
\n" ); document.write( "\"N=144A%2B12B%2BC\"

\n" ); document.write( "N = CBA base 7:
\n" ); document.write( "\"N=49C%2B7B%2BA\"

\n" ); document.write( "Set the two expressions for N equal to each other and solve the resulting equation for one variable in terms of the other two.

\n" ); document.write( "\"144A%2B12B%2BC=49C%2B7B%2BA\"
\n" ); document.write( "\"143A%2B5B=48C\"
\n" ); document.write( "\"5B=48C-143A\"
\n" ); document.write( "\"5B=%2845C-140A%29%2B%283C-3A%29\"
\n" ); document.write( "\"5B=%2845C-140A%29%2B3%28C-A%29\"
\n" ); document.write( "\"B=%289C-28A%29%2B3%28C-A%29%2F5\"

\n" ); document.write( "A, B, and C are positive integers less than 7, so in that last equation B, 9C, and 28A are all integers; that means \"3%28C-A%29%2F5\" must be an integer.

\n" ); document.write( "That means C-A must be a multiple of 5; and since C and A are positive integers less than 7, C=6 and A=1.

\n" ); document.write( "Then we have

\n" ); document.write( "\"B=9%286%29-28%281%29%2B3=29\"

\n" ); document.write( "But B has to be less than 6.

\n" ); document.write( "So there is no solution.

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