1.) The objective is to fill the 9x9 grid so that every row, every column, and every 3x3 box contains all the digits from 1 to 9.
2.) To solve the puzzle, a number can only appear once in:
Each Row: (9 horizontal squares)
Each Column: (9 vertical squares)
Each 3x3 Box: (The 9 squares surrounded by thick lines)
3.) Look for a number that appears frequently on the board. For example, if there are many 5s visible:
Follow the rows and columns that already have a 5.
You know a 5 cannot go in those lines.
By process of elimination, you will often find only one empty square left in a 3x3 box where that 5 can fit.
If you aren't sure a number goes in a specific spot, look elsewhere on the board.
Every correctly placed number acts as a "key" that unlocks the logic for the surrounding squares.
click on "RESET" button if the puzzle becomes unsolvable.
click on "CHECK LOGIC" button to find redundant numbers in any row or column.