a. each row,

b. column,

and

c. each of the nine 3x3 grids

has each number 1 through 9 exactly once.

Lets call it Sudoku puzzle's solution or SPS.

A grid with condition c. removed is called a Latin Square, LS.

1. (d2) how many 9x9 LS's are there?

2. (d4) And how many 9x9 SPS's ?