Anyone else flummoxed by Sudoku ?

[hattie43]

I keep trying but don’t get how to play . I’m on a long haul flight soon and would like to try again .
is there a method of starting to put the numbers in or do you literally go through everyone for every line .
anyone got any quick wins ?

I never start at the top and go from left to right, I start in the bottom right-hand square and go upwards checking each number in turn. Then I go downwards in the same way. Move left and do the same thing, and carry on until you have done all the ups and downs. By that stage you should have found a few obvious definites. Then start bottom left and go from left to right to left. That will find you a few more.

Then you repeat the entire exercise again, and this time hopefully the ones you already found will help you find more.

Use one of those propelling pencils with a rubber in the end, and in tiny writing, put the possibles in as you find them.

If for instance, you find a 1 in the top row of a box, and another 1 in the bottom row of the next box, you know that the final 1 has to be in the middle row of the final box somewhere. So pencil in a tiny 1 in each possible space. You can rule the wrong ones out later when you find some more 1's lower down.🙂

I try all the 1s, 2s etc, when I get to 9, I go backwards again, all the 8s, 7s etc.
I then try the boxes, then the rows.
I tend to go 1-9 9-1
Nobody taught me to do this, I’m sure there’s a method, I just do what works for me. I do masters in approx 8 minutes.

Try one with different difficulty levels so you can get used to using different techniques, start with easy and move up once you want more of a challenge.

Using small numbers in the boxes is useful, but I try to save that for closer to the end otherwise it gets too confusing. I usually alternate between checking boxes, checking lines, and checking numbers.

So as for what this means, to check a box, I look for boxes which only have a few spaces left. I've attached a picture, so come back in a few mins if it has not attached yet. This is a good example (it came up when I googled free sudoku puzzles).

The centre right box here has three spaces, so it's a good one to start with. The missing numbers are 6, 7, 8.

The 8 cannot possibly go in either of the bottom two squares of this box because there is already an 8 in the bottom of the three centre rows. The only place it can go is in the empty square I have highlighted blue. So I would put the 8 in there.

That leaves two squares in this box and the numbers 6 and 7. 7 in the bottom-right box rules out the bottom-right square, so it has to go in the middle bottom square of this box. The other square must contain the 6. That box is now complete.

I would then move onto the bottom middle box, and the bottom right box. Anything I can't work out yet, I just leave blank.

Do pretty much the same for each row and column, again starting with those with the least number of spaces.

If I get stuck I move onto numbers. So for example, in this "easy" puzzle, the number 5 appears 6 times, so there are only 3x more 5s to place in this puzzle. The 3 rows which must contain a no. 5 are row 3, 6, and 8. The three columns that must contain a 5 are 2, 4, 5, and the three boxes are top middle, centre, and bottom left.

Row 8 it has to be between the 8 and 1, because the only other space is in box bottom centre, which already contains a 5. So I can place a 5 here between 8 and 1 in the bottom left box.

That means there are only 2x more 5s to place. The only possible places are row 3, column 4/5 or row 6, column 4/5.

Row 3, column 4 already has a number 2 in it so the 5 in row 3 must be in column 5.

Therefore the last 5 has to be row 6, column 4.

The more you fill in like this, the more boxes, rows, columns and numbers will get to a point where there are only 3 possible spaces (easy-ish) or even 2 spaces (very easy unless you get 2 which could be in either place - don't guess for this, but can use the small number technique). or 1 space (then the answer can only be one thing).

The fun comes when you make a mistake and then fill in more numbers based on the mistake - then you have to rub things out and it gets messy! But if you start with only gaps of 3/2/1 then you shouldn't make too many mistakes.

Try sudoku.com

There are different levels to try, and it clearly highlights the numbers for you so that it is a bit easier to see patterns e.g if you click on an 8 in a box, it will highlight all the other 8s that are already there.

It also won't let you enter a wrong number, so you can then try it in another box.

Curiously, I have started doing a lot of sudoku puzzles and now I find it very hard to do a crossword - I used to be able to do the Guardian crossword almost every day - I guess it just uses a different part of your brain!

Practice, practice, practice.

Sudoku.com is good, as recommended above. I also like the New York Times ones, you get three a day (easy, medium, hard) and the interface very easy to use. For practicing before your flight.

this is useful, on Reddit. Will Mumsnet allow this link? Let’s see… https://www.reddit.com/r/sudoku/comments/116oqcq/new_to_sudoku_does_anyone_have_any_beginner_tips/

Try easy ones first!

Look at the three squares (by squares I mean the 3 x 3 squares, not the individual square cells) in the left hand column. If 2 of those squares have the same number already filled in (say 5), is it obvious where the 5 will go in third square? Repeat for all the numbers that are filled in in 2 squares in that column. Then do the same in the middle column of 3 squares. Then the same in the left hand column of 3 squares.

Next repeat the process but look at the rows across. So that will be 3 rows of 3 squares.

Once those are all filled in (these are the easy moves!) look at any row, column or square which has a lot of numbers filled in and look at the rows and columns that connect with them to see if you can rule out all the possible numbers for the blank cells apart from one. The knack is to find the ONLY number that can go in that cell. If you have a choice of two, forget it and move on.

Personally, I never make a note of the possible numbers on the page - it makes a mess. I force myself to remember where there are choices of two, everything else I dismiss.

So in the example posted by Bertie Botts above:

The missing numbers in the middle square right hand column are 6, 7 and 8. But 8 can ONLY go in the blue highlighted cell because if you put the 8 in either of the other two cells on the bottom row, you would have created a row/line across with 2 x 8s in it.

Similarly, the bottom right hand cell in that square can only be a 6, because if you put the 7 in there, you will have created a line down with 2 x 7s in it. So you know where the 8 and 7 go, now you can add the 6. Then you have done the full square.

That's how it works.

Snyder notation. Essentially you’re looking for places where a digit can be in only 2 places in a box and you pencil mark it, then if one pe coles digit gets replaced, you know the other is the penciled in number.
short explanation here: https://youtube.com/shorts/FDUwb3DWfTw?si=lqUM9ZofzTQHnyb4

helpful video here about what to do if you get stuck

I would recommend the linked YouTube channel “Cracking the cryptic” if you’re interested in sudoku. They tackle a different sudoku every day (really hard ones). It’s a really relaxing way to wind down in the evening.

Thanks everyone , I’ll have a good read and practice at the weekend .