How many possibilities are there for a 9×9 Sudoku?

6670903752021072936960
They discovered that the number of possible 9 by 9 Sudoku grids is N=6670903752021072936960 which is approximately 6.671×1021.

Is 9×9 Sudoku NP complete?

Sudoku is NP-complete when generalized to a n × n grid however a standard 9 × 9 Sudoku is not NP- complete.

How many squares are there in a 9×9 grid?

Rectangles

Board Size # Squares # Rectangles
6×6 91 441
7×7 140 784
8×8 204 1,296
9×9 285 2,025

Is there a formula for Sudoku?

For the second Sudoku, we have the following 10 equations: m+n=a. g+n+f=g+c⟹n+f=c. g+d=n….Sudoku 2.

Letter Number
f 2
g 3
m 5
n 4

Is Sudoku a NP hard problem?

Introduction. The generalised Sudoku problem is an NP-complete problem which, effectively, requests a Latin square that satisfies some additional constraints. In addition to the standard requirement that each row and column of the Latin square contains each symbol precisely once, Sudoku also demands block constraints.

How many valid Sudoku are there?

6,670,903,752,021,072,936,960 possible
There are 6,670,903,752,021,072,936,960 possible solvable Sudoku grids that yield a unique result (that’s 6 sextillion, 670 quintillion, 903 quadrillion, 752 trillion, 21 billion, 72 million, 936 thousand, 960 in case you were wondering). That’s way more than the number of stars in the universe.

What is 9×9 Sudoku?

The objective is to fill the 9×9 Sudoku grid with digits 1 to 9 such that each of these 9 digits appears in each row, each column and each 3×3 sub-grid once any only once. Don’t want to solve the same Sudoku puzzles again and again?

How do I use the Sudoku solver?

Choose one of the more than 50 Sudoku solvers via the menu button. Enter the known numbers and click the Solvebutton or Solve Cellbutton if you only need 1 number. Enter numbers PreviousNext If there is more than one solution, up to 10 solutions will be shown, and you can navigate between them using the Previousand Nextlinks.

How do I print Sudoku puzzles?

Start by selecting the difficulty level: easy, medium, hard, expert, evil. You can also print 4 sudoku per page or 6 sudoku per page. Then choose the print format: PDF or HTML.

How do I use the Smart solver to solve a puzzle?

Select a digit on the side of the grid first. Then click on the cells where you want to place the selected digit. After entering your puzzle, press either the “Solution” button for an instant solution or the “Solve with Smart Solver” button to bring up our smart solver.