Ключевые слова: active, activity, alzheimer, blank, brain, challenge, clever, crossword, develop, difficult, education, elderly, enjoy, exercise, focus, forget, fun, game, grid, hobbies, hobby, intelligence, keep, leisure, logic, math, mathematic, mathematical, memory, newspaper, number, old, older, paper, patience, patient, pen, pensioner, practice, problem, puzzle, relax, retired, senior, solution, solve, solving, square, sudoku, thinking,