Asian puzzle

Although many people believe that the sudoku was invented in Japan, its true father was an American. However, the game with the weird name, is extremely popular throughout the world.
The name means "lonely number" in Japanese, and it exists another version with letters, called Godoku.

Aim of the game

The square is divided into 9 big boxes, each divided in to another 9 smaller boxes. At least 17 figures, from 1 to 9, are placed in the boxes and the aim is to fill in a figure in each box. But, you can't put the same figure more than once in every line (vertical and horisontal), and the same thing with the larger boxes. They have to contain all figures, from 1 to 9.

Tips and tactics

To begin with, the easiest way to solve the sudoku, is to use two questions:
In what box should this figure be placed?
What figure should be put in this box?
There are numerous different tactics that can be found on the internet.