Sudoku X for Seniors: Getting Started, With a Printable Sample

Sudoku X for seniors is a natural step for readers who already enjoy Sudoku and would like something new without starting from zero. LogikLand has a Large Print version: one big grid per page, bold digits and instructions printed in large type. This article explains the puzzle, walks through a first grid, and gives the exact sizes and levels you can choose when you make a book.

Why Sudoku X is a good next step

In Sudoku X every row, every column and every 3 x 3 box contains the digits 1 to 9 once, as in classic Sudoku. One rule is added: each of the two long diagonals contains the digits 1 to 9 once as well. A reader who knows Sudoku has nothing to relearn, only one more group to watch. And because there is more to check, there are more places to find a digit.

The grey diagonals are a built-in aid

The two diagonals cross 17 cells (9 + 9, with the centre counted once). In the book they are shaded light grey, so the reader never has to count along a diagonal. We counted what each cell sees:

The grey cells are therefore the best-connected cells of the grid. They are also the best place to look when you are stuck, because a digit there is blocked from more directions.

A first session, step by step

The PDF has this grid on a Large Print page. Try one step before you read on: look at the grey diagonal that runs from the top left corner to the bottom right corner. It has no 8. Which of its cells can still take an 8?

• Row 1, column 1: column 1 already has an 8 (row 8).
• Row 2, column 2: column 2 already has an 8 (row 5).
• Row 3, column 3 holds 6 and row 7, column 7 holds 7.
• Row 4, column 4: column 4 already has an 8 (row 6).
• Row 5, column 5: row 5 already has an 8 (column 2). Row 6, column 6: row 6 already has an 8 (column 4).
• Row 8, column 8: row 8 already has an 8 (column 1).

One cell is left on the diagonal, row 9, column 9, so the 8 goes there. The reader found it without looking at a single box. Our suggestion, not a rule: tell new Sudoku X readers to begin with the grey cells for this reason.

The centre cell deserves a mention. It sits on both diagonals, so it must fit its row, its column, its box and the two diagonals at once. With 32 neighbours, its list of possible digits shrinks faster than that of any other cell, so a reader who checks it early often gets a quick result.

What the Large Print version does

• The default book title is "Large Print Sudoku X". Titles above a single grid are 28 pt.
• You choose 1, 2 or 4 grids per page; the default is 1. On 8.5 x 11 paper, one grid is 7 inches wide with 33.6 pt digits.
• The how-to-play guide has 3 pages with 17 pt text (4 pages with 15 pt text in 6 x 9), and a short version has a 30 pt title and 20 pt text.
• The solutions can be 1, 2 or 4 per page, with 2 as the default.
• Given digits are printed in bold, and the grey diagonals stay visible in the solutions too.

Which level to give

We solved the easy example above with a program that may use only the first technique, and it needed nothing else. Our suggestion, not a rule: for a first Sudoku X book, make about two thirds of the grids easy and one third medium.

Building the book

The Large Print Sudoku X assistant is in the Seniors tab, and it works with a free account. The FREE plan allows books of up to 50 pages. With one grid per page, the 3-page guide and two solutions per page, a book of 30 puzzles uses exactly 50 pages. Books made on the FREE plan are for personal use; commercial rights come with PRO and EXPERT.

Questions