SUDOKU is a fashionable Japanese puzzle in the form of a Latin magic square. "SU" in Japanese means "number" and "Doku" means "standing alone". In fact, this is a digital solitaire: you need to fill the cells of the 9x9 table with numbers from 1 to 9 so that in each row, in each column and in each selected 3x3 square, each number would appear only once.

The prototype of Sudoku without division into separate regions is found in the works of Leonard Euler (1707-1783) on magic squares. The puzzle in its modern form was first published in the American magazine "Dell Pensle Puzzles" in 1979. Its author is the architect Howard Garnes. And after the British newspaper "The Times" published the article "Sudoku", the triumphal procession of the puzzle began around the world. Sudoku began to print not only specialized, but also mass newspapers and magazines.

**Sudoku online** is also available on specialized puzzle sites.

Let's consider a Sudoku grid from a mathematical point of view. The question arises: how many different arrangements of numbers are there? Calculated: 6 670 903 752 021 072 936 960 placements. Billions of combinations can be used in each of the constellations by choosing a set of numbers, that is, the potential number of different options is unimaginably large.

Professionally composed puzzles should have a step-by-step solution, when, as a result of each logical move, another new number is entered. If we consider the simplest moves, then there are, in fact, only two. And each next step of the solution serves as an answer to the question: "What number can be in this cell?" or "Where is such and such a figure in this row?"

An experienced programmer can easily create a program that produces puzzles that have a logical solution. Such sudoku can be seen in most newspapers and magazines.

However, hand-made Sudoku is especially appreciated - in their solution there is a certain beauty and grace that no computer can provide.