# Sudoku 101

Grab a Sudoku puzzle and pencil to make time zip by on your next nonstop flight. With a few quick playing tips you will be counting and crossing your way through these brain teasers in no time. And don’t worry, no math is required!

What is Sudoku?

A logic-based game, Sudoku is a Japanese puzzle that tests your skill at solving number placements in a 9×9 grid. Popularized in 1986 by the Japanese puzzle company Nikoli, the puzzles can range from easy to extremely hard. As it flew across boarders, Sudoku eventually became an international hit in 2005.

How to Play

The objective of the game is to fill in all the blank cells with the numbers 1-9. The game board is 9×9 grid that is broken down into nine 3×3 grids, which are separated by bold lines. Each 3×3 grid, column and row on the game board must contain all the digits from 1 – 9. To play, use the given numbers to determine where the other numbers will fit in the puzzle. The given numbers cannot be changed at any time. Within the column, row and grid, the numbers 1-9 can only used once.

Solving Strategy

Scan the given numbers in the grid and look for obvious cell possibilities first. Fill in these cells.

Next try to solve each grid one at a time. Start with the first one in the upper corner and work through the rest trying to solve the 3×3 grid with its numbers. Take each number and check vertically and horizontally until you find the right cell. Then repeat this task with the rows and columns.

Now that you have tried solving by grid, column and row try scanning the puzzle by number. Start with one and fill in the possible open cells. Then continue with each number until no more obvious cells can be determined.

Continue working through the puzzle until all the cells are filled.

5 Tips for Sudoku Success

1. If a cell can be two different numbers, use a pencil to write down in the vacant cell the possible candidates for future reference. It’s best to write these possibilities in small numbers in the corners so not to confuse yourself while solving the remaining puzzle.
2. Note when numbers can only fit in one specific row or column within a grid. This can help eliminate other possibilities for other numbers within the same grid, row or column.
3. Look for hidden numbers. These will be cells where only one digit fits into the cell but the cell determination is only seen by cross referencing two or more points.
4. Find pairs. Look in rows and columns within a set 3×3 grid for pairs of numbers that can only fit in the same two cells. Pencil in these two numbers until you can determine which one belongs in each cell. This can also occur in triples.
5. Finally look for grids that already have two out of the three rows or columns filled in and try to simplify or eliminate the remaining possibilities in this section.

The more you play, the better you will get! Start with the easy puzzles and slowly work your way up to more challenging boards. You’ll be surprised at how quickly you will learn this number game!

Pick up a booklet of Sudoku puzzles or download the game to your smart phone or tablet to play on your next nonstop flight from Portland!

Photo caption: Old Day 2 – Sudoku, Tim Psych; jugando Sudoku, pena2