Tagged: family tree

Sudoku as a Genealogical Tool

Okay, maybe I’m a bit off the wall with this one, but I truly believe that completing Sudoku puzzles is a good way to develop your genealogical skills. To be more precise, this activity is a great way to increase your powers of deduction, logic, and inference. I’ll explain how in this post.

 What is a Sudoku Puzzle?

A Sudoku (pronounced “soo-doe-koo”), if you’re unfamiliar with it, is a number puzzle. Like most things, it has an interesting history all on its own. I won’t go into that here, but it actually didn’t originate in Japan as the name suggests. (Your assignment is to go research the history of Sudoku. There will be a test.)*

The puzzle is a grid made up of a total of 81 squares divided into smaller grids in nine smaller squares of nine numbers each (i.e. the numbers 1 through 9). The numbers are in a 3 by 3 arrangement in the smaller squares. To start, some of the 81 numbers in the larger puzzle grid are already filled in. Your task is to fill in the remaining numbers. The catch is that no number can be used twice in any of the smaller squares, vertical columns or horizontal rows. So how do you solve it with so little information?

First, you have to take a step back and ask yourself what the puzzle is already telling you. Even though it looks like there is no useful information at all (i.e. just a bunch of random numbers plugged in here and there), in fact there are logical inferences you can make from the numbers you have. Take a look at the example here:

Now, this is a major cheat since you would not very likely start off in a Sudoku puzzle with two full lines and one sub-grid filled in. However, I wanted to simplify it a bit for the purposes of showing you how the logical part works. What do you see?

The fact that some of the numbers are repeated more than others might be one thing you notice. The 3, 6, 7, and 9 appear more than the five other numbers. The 6 and 7 appear most often. Therefore, we have more information about the placements of the 6 and 7 than we do about any of the other numbers. This is a good place to start, then.

What do we do with that? If you look at the possible locations of the next number 6, you’ll see there are just too many possibilities to say for certain where that next 6 will go. There are from two to four possible locations for any of the squares that do not yet contain a 6.

Moving on, what about the 7? In the three centre sub-grids, from the top sub-grid to the bottom sub-grid, there are three, five, and five possibilities respectively. That’s not enough information. In the left-centre sub-grid, there are two possibilities for placement. Again, this is not enough information to tell us where to put the 7.

But look at the bottom right-hand grid. There is only one possible square in which to place a number 7: the bottom line, middle square. I hope you see this. You have just used a logical inference.

Why is This Relevant?

In order to complete a Sudoku successfully you need to use logic, inference, and deduction. It is just exactly this kind of careful examination of the clues you have that you’ll use in sorting out the possibilities for relationships in family trees and pedigrees. In order to research your family history you often need to use…logic, inference, and deduction.

Don’t be fooled. A Sudoku is not about the numbers or about mathematics (although there is mathematical theory that applies to it). You don’t have to be a whiz at arithmetic to solve one. I have heard many people say, “Oh, I don’t do Sudokus. I’m no good at math.” You don’t have to be! Solving the puzzle is all about you reasoning effectively.

If you’re already a whiz at Sudokus, but you haven’t started researching your family history, I ask you: “Why not?” You’ll likely be very good at it. The skills you honed while solving Sudokus are exactly the same kinds of skills, among many others, that university history professors spend 3 or 4 years trying to drill into their students’ heads. In other words, these skills are excellent building blocks for learning how to conduct historical and genealogical research.

If you’ve never done a Sudoku puzzle and you’re interested in family history research, start doing a daily Sudoku. It won’t get you any closer to learning your great-great-grandfather’s name, but you will have a good grounding on how to figure out who he is from a dozen others of the same name living in the same county once you do start researching because now you will have the powers of logic, inference, and deduction you’ll need to do that. The rest is finding the resources to apply your new skills to in order to create your family tree. (But that’s another blog post for another day.)

I’m Convinced, Where do I Find One?


Most daily newspapers run a daily Sudoku. In the Eastern Ontario area where I live, we have a weekly free newspaper that always features a Sudoku. You can also buy whole books of Sudoku puzzles at bookstores like Chapters-Indigo or at department stores or grocery stores with magazine sections. So they’re not hard to find.


The CBC website has a daily Sudoku on their website in their Games pages (on the main page, click on “More” then look for the “Games” link under the “Sections” heading; scroll down to find the “Sudoku Daily” link under the “Diversions” heading) . The Open Directory Project has dozens of links to daily Sudoku puzzles at http://www.dmoz.org/Games/Puzzles/Brain_Teasers/Sudoku/ .

[Addendum: Kelly Leary, of K.B. Genealogy & Research in Fort Pierce, Florida, informs me that there is a Sudoku app for the iPad, iPhone, and iPod Touch. It’s free!]

So do go and get a Sudoku and start working on it! And let us know how it turns out by leaving a comment!

Contact Pearce Heritage Research at www.pearceheritageresearch.ca if you need help getting started on your family history research. Tell us that you read our Sudoku blog entry and we’ll give you a half-hour free genealogy consultation (offer good until December 31, 2012). Fill in the message area on our Contact Us page and tell us you read this blog post.

*Just kidding about the test. And the assignment.