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Puzzle #211: Can you work out what number Mary crosses out?

Can you solve this week’s arithmetical puzzle, Cross purposes? Plus the answer to puzzle #210

1 March 2023

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#211 Cross purposes

Set by Peter Rowlett

Debbie and Hoi are playing a game where they take turns to cross out numbers written on a piece of paper.

Each player must cross out a divisor or a multiple of the number most recently crossed out. The first player who is unable to cross out a number loses.

Hoi goes first and crosses out 11. Debbie smiles, knowing she can now win in three moves. What number does she cross out?

2 3 4 5

7 11 15 19

33 35 38 51

55 76 77 95

Solution next week

#210 …

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