How to Figure Out a Super Sudoku

Solve a super sudoku with a pencil so you can erase numbers if you need to.

A traditional sudoku puzzle features a nine square by nine square grid in which you place the digits from 1 to 9 in the boxes so that each column, row and three-by-three box contains each digit. A super sudoku increases that size to 16 squares by 16 squares and uses numbers, letters or a combination of both. Solving strategies are similar for both types of sudoku puzzle, but super sudokus tend to be more challenging and time-consuming.

Instructions

1. Search the super sudoku grid for the four-by-four box square that has the highest concentration of symbols already filled in. Determine which symbols are missing from that area. Look horizontally and vertically from each empty box in that section to eliminate possibilities for that box, using a process of elimination to determine which symbol to place in the box. Use this strategy for rows and columns as well.

2. Find the symbol that appears most frequently on the grid and locate the four-by-four box squares where that symbol doesn't appear. Search horizontally and vertically from the empty boxes in each square to eliminate possibilities and determine the proper location for the missing symbol. Repeat this process for the remaining symbols.

3. Pencil in placeholder numbers when you've narrowed your possibilities for a box to two or three choices. For example, if you've deduced that the digits 2 and 4 are the only possible choices for a particular box, lightly pencil those numbers into the box.

4. Examine sets of placeholders to eliminate symbols for other empty boxes in that area. For example, if you have a row with three empty boxes that are missing the numbers 2, 4 and 5, and your placeholders indicate that two of those boxes must contain a 2 and 4, in some order, you can conclude that the 5 belongs in the third remaining box.

5. Determine symbol placement by trial and error when all other strategies fail. Start from a box where you've narrowed the possibilities to two symbols and lightly write one of those symbols in the box. Solve the puzzle as normal from that point; if that path leads to two of the same symbol in the same row, column or square, your choice was incorrect. Erase all of the symbols entered during the trial and error and use the other symbol in the starting box.

Tips & Warnings

• Repeat steps 1 and 2 frequently as you solve the super sudoku. As you fill in boxes, the choices will be narrowed for boxes in the surrounding area.

• Use a pencil or pen of a different color when using trial and error to help distinguish those symbols from ones that you're certain are in the proper box.

References

• Penny Dell Puzzles: How to Solve Sudoku