Embed Size (px)
DESCRIPTION
Solving a Sudoku Puzzle. By Marlene Walther ATeacherFirst.com. Rows go across …. Use the numbers from 1 to 9 only!. Each row has 9 cells across. The numbers 1 to 9 will appear only once in each row. There are 9 rows in a puzzle. Columns go down …. - PowerPoint PPT Presentation
Citation preview
Solving a Sudoku Puzzle
By Marlene WaltherATeacherFirst.com
2
Use the numbers from 1 to 9 only!
The numbers 1 to 9 will appear only once in each row
Rows go across …
Each row has 9 cells across
There are 9 rows in a puzzle
3
The numbers 1 to 9 will appear only once in each column
Each column has 9 cells down
Columns go down …
There are 9 columns in each puzzle
4
The numbers 1-9 will appear only once in each 3 x 3 block There are 9 blocks in each puzzle
Blocks …
5
We have 9 columns
And we have 9 blocks
So …
We have 9 rows
6
Look at the three blocks on the left side of the puzzle
Notice which numbers are repeated (1, 3, 4, 7)
Notice that the number 3 is in Column 1 and Column 2
Step #1
7
The number 3 can appear only once in each column
The number 3 is already in Column 1 and Column 2, so where will it go in Column 3? The number 3 must appear in the bottom block because it is in the top two blocks already
Step #1
8
The number 3 cannot appear in any column or row where it is already
It must go here – the only place left
The number 3 cannot appear in any block where it is already
Step #1
9
Write the number 3 in the cell
3
Step #1
10
Look at the number 1 in the three blocks on the left
3
The number 1 cannot appear in those two columns again
There is only one cell in the third column where the number 1 can go. Can you find it?
Step #2
The number 1 cannot appear in the top or bottom block
11
3
1
Did you get it right?
Step #2
12
Look at the number 4 in the first three blocks on the left
1
3
The number 4 cannot appear in those two columns or those two blocks again
There is only one cell in the top block where the number 4 can go.
Can you find it?
Step #3
13
3
1 Did you get it right?
4
Step #3
14
Look at the number 7 in the middle three blocks
1
3
The number 7 cannot appear in those two columns againThere is only one cell in the top middle block where the number 7 can go.
Can you find it?
Step #4
4
15
3
1 Did you get it right?
47
Step #4
16
Look at the 7’s in the top three blocks and the blocks on the left
4
1
3
The number 7 cannot appear in any row or column twiceThere is only one cell in the top block where the number 7 can go.
Can you find it?
Step #5
7
17
3
1 Did you get it right?
47
7
Step #5
18
Notice all the 7’s in the puzzle.
1
3
There is one 7 in every block except the bottom right block
There is only one cell where the number 7 can go.
Can you find it?
Step #6
74
7
19
3
1
Did you get it right?4
7
77
Step #6
20
3
1
Where will the 4 go in this block?
4
7
77
Would you like a hint?
Step #7
21
3
1
4
7
77
Step #7
22
3
1
Did you get it right?4
7
7
7 4
Step #7
23
3
1
Fill in the number 4 in the bottom right block
There is only one cell where it can go
4
7
7
7 4
Step #8
24
3
1Did you get it right?
4
7
7
7 4
4
Step #8
25
3
1
There is only one possible cell for the number 3 in the bottom right block
Where does the number 3 go?
Would you like a hint?
4
7
7
7 4
Step #9
4
26
3
1There is only one cell where the number 3 can go
Can you find it?
4
7
7
7 4
4
Step #9
27
3
1Did you get it right?
4
7
7
7 4
4
3
Step #9
28
3
1
Where will the number 3 go in the middle block?
Would you like a hint?
4
7
7
7 4
43
Step #10
29
3
1There is only one possible place for the number 3 in the middle block
4
7
7
7 4
43
Step #10
30
3
1
Did you get it right?4
7
7
7 4
43
3
Step #10
31
3
1
Where will the number 3 go in the top middle block?
There is only one cell where it can go
4
7
7
7 4
43
3
Step #11
32
3
1Did you get it right?
4
7
7
7 4
43
3
3
Step #11
33
3
1
Can you figure out where the number 2 will go in the top left block?
Would you like a hint?
4
7
7
7 4
43
3
3
Step #12
34
3
1There is only one possible cell for the number 2 in the top left block.
4
7
7
7 4
43
3
3
Step #12
35
3
1Did you get it right?
4
7
7
7 4
43
3
3
2
Step #12
36
3
1
There are only two cells open in the top middle block
You can use the numbers 1-9 only once in each block
Which two numbers must go in those two cells?
4
7
7
7 4
43
3
3
2
Step #13
37
3
1
The numbers 2 and 9 must go in this block
There is only one place for the number 2
Would you like a hint?
4
7
7
7 4
43
3
3
2
Step #13
38
3
1
The number 2 cannot go in the top row because there is a 2 in that row
Therefore, 2 must go in the third row
And then the number 9 must go in the top row (the only cell remaining in that block)
4
7
7
7 4
43
3
3
2
Step #13
39
3
1
You can now see that the top middle block has all the numbers from 1-9 in it
Please note that no number is repeated in that block
4
7
7
7 4
43
3
3
2
2
9
Step #13
40
3
1
Where will the 3 go in the top right block?
4
7
7
7 4
43
3
3
2
2
9
Step #14
3
Did you get it right?
41
3
1
Where will the 5 go in the top left block?
4
7
7
7 4
43
3
3
2
2
9
Step #15
3
5
Did you get it right?
42
3
1
Where will the 9 go in the top left block?
4
7
7
7 4
43
3
3
2
2
9
Step #16
3
59
Did you get it right?
43
3
1
There is only one number to go in the top left block
What number has not been used?
4
7
7
7 4
43
3
3
2
2
9
Step #17
3
59
8
Did you get it right?
44
3
1
There is only one number to go in the top row
What number has not been used?
Did you get it right?
4
7
7
7 4
43
3
3
2
2
9
Step #18
3
59
8 6
45
3
1
There is only one number to go in the second row
What number has not been used?
Did you get it right?
4
7
7
7 4
43
3
3
2
2
9
Step #19
3
5
98 6
5
46
3
1
There are two numbers that need to go in the top right block
What numbers have not been used?
4
7
7
7 4
43
3
3
2
2
9
Step #20
3
59
8 6
5
47
3
1
The two numbers are 9 and 1
The 9 can go in only one cell because there is a 9 in one of the columns
4
7
7
7 4
43
3
3
2
2
9
Step #20
3
59
8 6
59 1
Did you get it right?
The number 1 will go in the last cell.
48
3
1
There are two numbers that need to go in this row
What two numbers have not been used?
4
7
7
7 4
43
3
3
2
2
9
Step #21
3
59
8 6
59 1
49
3
1
The 2 cannot go in the second column twice, so it must go in the 5th column
4
7
7
7 4
43
3
3
2
2
9
Step #21
3
59
8 6
519
The 8 cannot go in the 5th column, so it must go in the 2nd column
8 2
50
3
1
Fill in the missing number in this column
4
7
7
7 4
43
3
3
2
2
9
Step #22
3
59
8 6
519
8 26
51
3
1
Fill in the missing number in this column
4
7
7
7 4
43
3
3
2
2
9
Step #23
3
59
8 6
519
8 26
9
52
3
1
Which two numbers are missing in this column?
4
7
7
7 4
43
3
3
2
2
9
Step #24
3
59
8 6
519
8 26
9
The number 6 can go in only one possible cell because already appears in one of the rows
Fill in the two numbers
2
6
53
3
1Fill in the missing number in this column
4
7
7
7 4
43
3
3
2
2
9
Step #25
3
59
8 6
519
8 26
9
2
65
54
3
1Fill in the missing number in this block
4
7
7
7 4
43
3
3
2
2
9
Step #26
3
59
8 6
519
8 26
9
2
65
5
55
3
1
There are three numbers missing from this block.
Which numbers are they?
Can you figure out where the 8 goes?
4
7
7
7 4
43
3
3
2
2
9
Step #27
3
59
8 6
519
8 26
9
2
65
5
8
56
3
1
Where does the number 1 go in this block?
There is only one place it can go.
4
7
7
7 4
43
3
3
2
2
9
Step #28
3
59
8 6
519
8 26
9
2
65
5
8 1
What number is left to go in this block?
Write it in.
5
57
3
1
Which number is left to go in this column?
Fill it in.
4
7
7
7 4
43
3
3
2
2
9
Step #29
3
59
8 6
519
8 26
9
2
65
5
8 1
5
1
58
3
1
Which two numbers still need to go in this column?
The 8 can go in only one possible cell.
Write it in.
Then write in the last number.
4
7
7
7 4
43
3
3
2
2
9
Step #30
3
59
8 6
519
8 26
9
2
65
5
8 1
5
1 89
59
3
1
Which number needs to go in this row?
Write it in.
4
7
7
7 4
43
3
3
2
2
9
Step #31
3
59
8 6
519
8 26
9
2
65
5
8 1
5
1 891
60
3
1
Fill in the two numbers that must go in this row.
The number 5 can go in only one cell.
The number 9 will go in the other one.
4
7
7
7 4
43
3
3
2
2
9
Step #32
3
59
8 6
519
8 26
9
2
65
5
8 1
5
1 891
5 9
61
3
1
Fill in the number that is missing in this row.
4
7
7
7 4
43
3
3
2
2
9
Step #33
3
59
8 6
519
8 26
9
2
65
5
8 1
5
1 891
5 9
2
62
3
1
The 2 and 6 are missing from this row.
Where will they go?
4
7
7
7 4
43
3
3
2
2
9
Step #34
3
59
8 6
519
8 26
9
2
65
5
8 1
5
1 891
5 9
2
2 6
63
3
1
Fill in the missing numbers in this row.
4
7
7
7 4
43
3
3
2
2
9
Step #35
3
59
8 6
519
8 26
9
2
6
5
5
8 1
5
1 891
5 9
2
2 66 9 4
Congratulations on completing a Sudoku puzzle!
![There is no 16-Clue Sudoku: Solving the Sudoku … Sudoku.pdfarXiv:1201.0749v1 [cs.DS] 1 Jan 2012 There is no 16-Clue Sudoku: Solving the Sudoku Minimum Number of Clues Problem Principal](https://img.dokumen.tips/doc/110x75/5af8051d7f8b9a8d1c9105a7/there-is-no-16-clue-sudoku-solving-the-sudoku-0749v1-csds-1-jan-2012-there.jpg)