we turn coffee into puzzles

Pentominoku The ten numbers 0--9 must each appear exactly once in each row and column, with no repeated entries in any pentomino region. In addition, there are exactly two pentominos that contain only the numbers 1--5, and exactly two pentominos that contain only even numbers. Appeared as an inside-back-cover contest in Math Horizons magazine, a publication of the Mathematical Association of America, September 2006. A pentomino is a shape made of five orthogonally connected square cells. Every one of the twelve possible pentominos appears in this puzzle.