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Advent calendar 2018

17 December

For \(x\) and \(y\) between 1 and 9 (including 1 and 9), I write a number at the co-ordinate \((x,y)\): if \(x\lt y\), I write \(x\); if not, I write \(y\).
Today's number is the sum of the 81 numbers that I have written.

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Tags: numbers

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