We continue with 3 puzzles each month. Something for everyone!
Clueless?
We start with a Sudoku puzzle in progress, where it appears that there are no more obvious or not-so-obvious clues. Can you find the hidden clue in Puzzle #116?
(The answer follows the conclusion of Puzzle #118, the feature puzzle for August)
Logic Puzzle
Difficult rating … 2/10
(Rating based on puzzles not requiring advanced techniques)
Puzzle #117 should be fun!
Feature Puzzle
Difficult rating … 3/10
(Rating based on puzzles requiring advanced techniques)
Dan recommends the following Steps to complete the puzzle.
Step 1: Sudoku Pairs, Triplets and Quads – See September 2015
Step 2: Turbos & Interaction – See October 2015
Step 3: Sudoku Gordonian Rectangles and Polygons – See November 2015
Step 4: XY-Wings & XYZ Wings – See December 2015
Step 5: X-Wings – See January 2016
Step 6: DAN’S YES/NO CHALLENGE
Step 7: DAN’S CLOSE RELATIONSHIP CHALLENGE
Step 8: AN EXPANSION OF STEP 7Steps 1-5 are relatively common techniques and are explained in the TI LIFE articles above. Steps 6-8 are covered in detail, in Dan’s book.
PUZZLE PREPARATION
Prior to utilizing Steps 1-8, complete the 5 Steps of Puzzle Preparation …
- FILL IN DATA FROM OBSERVATIONS
- FILL IN OBVIOUS ANSWERS
- FILL IN NOT-SO-OBVIOUS ANSWERS
- MARK UNSOLVED CELLS WITH OPTIONS THAT CANNOT EXIST IN THOSE CELLS
- FILL IN THE OPTIONS FOR THE UNSOLVED CELLS
We observe the following … C4R5=3. C1R8=8.
C5R4 & C6R6 have options 5 & 6. Then, C5R5 & C6R6 have options 8 & 9.
In box 7 a 3 can only exist as an option in C3R7 & C3R8; therefore, a 3 cannot exist as an option in in C3R1, C3R2, C3R4 & C3R6.
In box 7 a 6 can only exist as an option in C1R9 or C2R9; therefore, a 6 cannot exist as an option in C7R9 & C8R9.
In box 3 an 8 can only exist as an option in C8R1 & C8R2; therefore, a 8 cannot exist as an option in C8R4, C8R5, & C8R6.
Check out row 9. Options 2 & 4 can only exist in C5R9 & C8R9.
Now your grid should like Example #118.1 below:
This completes Puzzle Preparation Steps 1-4, but before we will fill in options for all unsolved cells, we will do a quick check for potential Step 6 exercises.
As in previous articles, we determined a particular number was a potential for a successful Step 6 exercise if that number appears as a given answer in 3 separate boxes, such that the boxes are not side-by-side, nor over each other. Which numbers do you see that are good candidates? Yes, 2 and 4.
We will first pick the number 2 and perform the exercise. At this point at your home, you would put green tokens on two starter cells that are 2’s and black tokens on all unsolved cells that could have the option 2. For purposed of illustration, in Example #118.2 below we will highlight two starter cells in green, and the unsolved cells that could be a 5 in yellow (vs black).
We have chosen C5R9 & C8R9 as our starter cells. We first assume C5R9 is the 2 and put a Y in that cell to indicate it is the 2 and see how it affects the yellow cells, placing a Y or N in the affected cells.
Next, we assume C8R9 is the 2 and place a y in that cell, and see how it affects the yellow cells, placing a y or n in those cells.
We can see that regardless of which starter cell is a 2, C1R3 and C5R1 cannot be a 2. Also, re-gardless of which starter cell is the 2, C6R3 is a 2. So C6R3=2.
By performing this exercise prior to filling in the options for the unsolved cells will give us some answers, reducing the amount of work filling in the option for the unsolved cells. We now have Example #118.3 below:
Now, in box 2 a 4 can only exist as an option in C5R2 & C6R2; therefore, a 4 cannot exist as an option in C1R2, C2R2 & C3R2. Therefore, C2R3=4. Then, C3R6=4, C8R5=4, C9R8=4, C5R9=4, C6R2=4, C5R7=2, C8R9=2, C9R4=2, C1R5=2, C3R1=2.
This puzzle is easily solved at this point, giving us Example #118.4 below:
May the gentle winds of Sudoku be at your back.
By Dan LeKander, Wellesley Island
Clue for Puzzle #116 … did you find the clue? If not, read on.
Check column 6. What do you see?
We see that C6R1, C6R2, C6R3 & C6R9 cannot be a 2 or 6; therefore, C6R5 & C6R8 must have options 2 & 6. Then, C6R4=4. Continue on and solve the puzzle!
Editor's Note: Note: we went into the 100s in May 2022
Now here are Puzzles #116, #117, & #118
"I keep saying . . . when we published the final article in Dan's Series of steps to learn the logic of Sudoku, I never in a zillion years thought that Dan would so graciously offer to do one or two puzzles for us each month - and he has done so without my asking. Now we are up to 3!
Then his wife, Peggy, does the proof reading and I only have to post in on TI Life. We would love to know how many you have solved. (Many, darn it, have stumped me, but I look forward to them each month.)
In May someone wrote to ask how to fill them out online. Unfortunately, you need to print them yourself - but that is easy to do and I know you will have just as much fun.
And, if you have not already done so, I suggest you purchase Dan’s book: