Puzzles

Multigraphs
Puzzles

Multigraphs

By Stephen Meskin
I came across the following interesting problem from the 61st Annual International Mathematical Olympiad (IMO), which was held remotely on Sept. 20 & 21, 2020. The IMO is the world’s leading mathematical competition for high school students.

A Crossnumber Puzzle With Squares
Puzzles

A Crossnumber Puzzle With Squares

By Stephen Meskin
For those who remember the puzzles I posed in my “Crossnumber Puzzles” (January/February 2019), the puzzles this time are to fill a 4 × 5 matrix in which each of the nine clues (four across and five down) is the same: a perfect square with the proviso that all nine perfect squares are different.