AMC 10 Step by Step

2002 AMC 10BProblem 16P16-20~4 minPrint

Diophantine Equations Number Properties Bound the quantity above/below or estimate to pin it down Organized listing / direct enumeration

For how many integers $n$ is $\dfrac n{20-n}$ the square of an integer?

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Problem © Mathematical Association of America (MAA), American Mathematics Competitions. Reproduced for non-commercial educational use. Solution and commentary are original to this site. Also appeared as 2002 12B #12.