AMC 10 Step by Step
2019 AMC 10AProblem 20P16-20~5 minPrint

The numbers 1,2,,91,2,\dots,9 are randomly placed into the 99 squares of a 3×33 \times 3 grid. Each square gets one number, and each of the numbers is used once. What is the probability that the sum of the numbers in each row and each column is odd?

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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.