Fill in the blank small triangles with a 1 - 9 (or 1 - 4 for 4X puzzles). Each number can appear only once in each side, inner triangle, and colored crossbar).
Fill in the blank small triangles with a 1 - 9 (or 1 - 4 for 4X puzzles). Each number can appear only once in each side, inner triangle, and colored crossbar).