Winning strategy for a 2024 cell-row in the Centro
Source: Centroamerican and Caribbean Math Olympiad 2024 P2
October 17, 2024
OMCCcombinatoricswinning strategy
Problem Statement
There is a row with cells. Ana and Beto take turns playing, with Ana going first. On each turn, the player selects an empty cell and places a digit in that space. Once all cells are filled, the number obtained from reading left to right is considered, ignoring any leading zeros. Beto wins if the resulting number is a multiple of , otherwise Ana wins. Determine which of the two players has a winning strategy and describe it.