Sudoku
Yes the word how can be an adverb. For example, "How did you solve the sudoku puzzle? Other times it can be a conjunction: "He forgot how the switches had been set."
No, 325 is not a perfect square however 324 is a perfect square.
38 is not a perfect square. Its square root is a fraction and the square root of a perfect square is always an integer.
No- the closest perfect squares are 36 (perfect square of 6) and 49 (perfect square of 7)
It is called sudoku
Its basically a math puzzle, so a type of puzzle.
One could visit SudokuProfessor or SudokuDragon to find strategies on how to complete a Sudoku Puzzle. Also, if one happens to have a Sudoku Puzzle Book, at the front page is usually a guide to how to complete a Sudoku puzzle. Once you know how to, they are really fun and good for keeping the mind active.
Sudoku
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The puzzle known as "Al Escargot" (the snail) is currently considered the hardest Sudoku puzzle. It was created by a Finnish mathematician called Arto Inkala. One of the hardest Sudoku books available is "Extreme Sudoku" by Antoine Alary, not to be confused with "X-TREME Sudoku" by Nikoli & Co. or "Sudoku Xtreme" by Christopher Monckton, which are both an order of magnitude easier.
You need more information.
It depends on the puzzle.
a Sudoku puzzle is a test of logic while a crossword puzzle is a test of how like a thesaurus you are or a test of general knowledge. which one if better is a matter of opinion, but i suppose one might stimulate the brain than the other, if that is what you mean by better.
Sudoku does not have any addition. You just have to make sure that each row, column and 'sub square' has each of the nine digits (1-9) only once.
Sudoku
Sudoku and crossword puzzles