Definition 1 Grid

Here is two grids. We use grid to describe a puzzle. The two grids are all empty. The left one has coordinate outside.

Definition 2 Regions

Regions mean Row, Column and Box.

(1) Numbers horizontal makes a row, numbers vertical makes a column  

(2) Area enclosed by thick lines make Boxes

Boxes have their names.

Definition 3 Cells and coordinate

(1) Cells is the small square

(2) Cells in RowX and ColumnY will be called XY

Such like A1, B9 or C8.

Definition 4 Givens and Answer

(1) The numbers given to us are given numbers

All the given numbers in a grid forms an Initial Grid.

(2) The white cells are waiting us to fill

When you write numbers in grid, these filled numbers are modifiable. But if you are sure, the given numbers and the filling ones are called value.

(3) If all the white cells are filled fitting the rules, we will get a solution.

An eligible sudoku should have only one solution.

Practice

① In 4x4/6x6/9x9 Sudoku, C3 stays in which box?

Answer

① 4/3/1