Explanation of the 3x3 magic square - Magisch vierkant
Sudoku - Your attention. Killer sudoku, easy level, #095 Killer Sudoku 9x9 (Sum-do-ku, Sums Number Place, Kikagaku Nampure, Sums Sudoku, Samunamupure) divided by a smaller square of 3x3 cells. The entire playing
Magic square - Wikipedia
How Many 3×3 Magic Squares Are There? Sunday Puzzle – Mind Your Decisions