I was first introduced to this number game by my high school chemistry teacher. At the time, she gave it to us as a form of extra credit, but after finishing one I was hooked! I went and brought a book of it so that I could practice.
The objective of the game is to fill a 9×9 grid with the digits so that each column, row, and each 3×3 sub-grid contain all of the digits from 1 to 9. The puzzle usually will already have some numbers filled in already.
For beginners or those that are attempting to complete their first puzzle, here are some tips to success!
1) Never guess or put numbers in randomly.
2) Remember, each row, column, and sub-grid can only contain each of the digits only once, so if a digit appears in a row, it can not be in any other cell in the row.
3) Try to start with the number that appears most frequently in the puzzle.
There are many other tips that I have come to use over the years, but I believe the struggle is half the fun!