Similar to Latin squares, the number of sudoku grids can be "reduced" by noting that there is a one-to-one correspondence with a partially standardized form, in which the first block has the canonical labels and both the top row and leftmost column are sorted (for as much as the rules allow, i.e. within blocks and the stacks/bands themselves). For a grid with blocks, each such reduced grid corresponds to formula_15total grids, which is 9! × 722 or 1,881,169,920 for the normal 3×3 Sudoku. This reduction is always one-to-one, unlike the action of the full set of validity preserving transformations ('Sudoku symmetries') discussed below.