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This instructable provides step by step instructions to complete a Sudoku puzzle by simple process of elimination.

One of the things I that drove me crazy about Sudoku is how difficult it is to return to a puzzle if you get interupted. This system allows you to walk away from a puzzle at any time and return exactly where you left off.[/vc_column_text][vc_tour][vc_tab title=”Step 1: What you need to begin” tab_id=”1407309619-1-92″][vc_column_text]

You need:

1. A sudoku puzzle. I enlarged this one (which was the puzzle that appeared on Sudoku.com on July 8, 2006.) to make photography easier. I find this system works better on larger puzzles.

2. A pencil, Not a pen. A pencil.

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You see, a Sudoku puzzle is missing a grid. Once you put in this grid, it is sooo much easier.

Enter the numbers 1 through 9 in a “tic-tac-toe” pattern in every blank box.[/vc_column_text][/vc_tab][vc_tab title=”Step 3: Erase “Across“” tab_id=”1407309992347-2-9″][vc_column_text]

For each number that is preprinted in the puzzle, you will start erasing that number from the appropriate grids you just wrote in.

So the first number (in the upper right corner) is a “6”. Erase every other “6” in that row. Once you have completed the erasing, draw a line across the top of the number to indicate that you have cleared out that line.[/vc_column_text][/vc_tab][vc_tab title=”Step 4: Erase Down” tab_id=”1407309993842-3-0″][vc_column_text]

Now, for that same number “6”, erase the corresponding “6”‘s in every box in the same column. Once you have completed erasing, draw a line down the edge of the number to indicate that you have completed this step.[/vc_column_text][/vc_tab][vc_tab title=”Step 5: Erase “All Around“” tab_id=”1407309994729-4-10″][vc_column_text]Ok, last step for the first number “6” Erase all the “6”s in the same quadrant. Then draw a circle around the number to indicate you have completed this step.

Now you have eliminated all the sixes from all the other blocks. That indicates that a Six canot appear in any of those blocks.

Keep going, repeat those same three steps for all the other pre-printed numbers in the puzzle.[/vc_column_text][/vc_tab][vc_tab title=”Step 6: Repeat for all the pre-printed numbers” tab_id=”1407309995801-5-10″][vc_column_text]

Just repeat thos three steps for each number that was printed in the puzzle. The purpose of the down, across, and circle marks on each number is to provide for any interruption that may occur when solving the puzzle. By drawling those lines you can always tell exactly where you left off. If the number has all three marks, you can be sure that all of the corresponding numbers have been eliminated from the puzzle. YOu can effectively forget about that block now.

Let’s see what the result of all that erasing was.[/vc_column_text][/vc_tab][vc_tab title=”Step 7: Locate Answers” tab_id=”1407310465410-6-4″][vc_column_text]

By process of elimination you will have done so much erasing in some blocks that only one number is left. Guess what. THat is the answer for that block. Congratulate yourself.

Write that number large in the block, then treat it like a preprinted number. Eliminate all the across, down and around numbers as you have already done so many times before.

In this image, the red pen points point to all the answers that were provided just by doing the initial erasing.

We have not yet begun to think!

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