Ключевые слова: activity, blank, brain, brain activity, brain gymnastics, brainteaser, challenge, competition, conundrum, crossword, detail, education, educational, entertainment, exercise, game, grid, hobby, japanese, learning, leisure, leisure activities, logic, logic puzzle, macro, math, math game, mathematics, mental games, number, numerical, object, pastime, patience, pencil, play, popular, problem, relax, school, solution, solve, solving, square, sudoku, sudoku answer, sudoku game, teaser, think, trainer,