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Solving a Sudoku Puzzle By Marlene Walther ATeacherFirst.com.

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Presentation on theme: "Solving a Sudoku Puzzle By Marlene Walther ATeacherFirst.com."— Presentation transcript:

1 Solving a Sudoku Puzzle By Marlene Walther ATeacherFirst.com

2 2 Use the numbers from 1 to 9 only! The numbers 1 to 9 will appear only once in each row 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 There are 9 rows in a puzzle

3 3 The numbers 1 to 9 will appear only once in each column The numbers 1 to 9 will appear only once in each column Each column has 9 cells down Each column has 9 cells down Columns go down … There are 9 columns in each puzzle There are 9 columns in each puzzle

4 4 The numbers 1-9 will appear only once in each 3 x 3 block The numbers 1-9 will appear only once in each 3 x 3 block There are 9 blocks in each puzzle There are 9 blocks in each puzzle Blocks …

5 5 We have 9 columns We have 9 columns And we have 9 blocks And we have 9 blocks So … We have 9 rows We have 9 rows

6 6 Look at the three blocks on the left side of the puzzle Notice which numbers are repeated (1, 3, 4, 7) Notice which numbers are repeated (1, 3, 4, 7) Notice that the number 3 is in Column 1 and Column 2 Notice that the number 3 is in Column 1 and Column 2 Step #1

7 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 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 The number 3 must appear in the bottom block because it is in the top two blocks already Step #1

8 8 The number 3 cannot appear in any column or row where it is already The number 3 cannot appear in any column or row where it is already It must go here – the only place left It must go here – the only place left The number 3 cannot appear in any block where it is already The number 3 cannot appear in any block where it is already Step #1

9 9 Write the number 3 in the cell 3 Step #1

10 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 11 3 1 Did you get it right? Step #2

12 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 13 3 1 Did you get it right? 4 Step #3

14 14 Look at the number 7 in the middle three blocks 1 3 The number 7 cannot appear in those two columns again There is only one cell in the top middle block where the number 7 can go. Can you find it? Step #4 4

15 15 3 1 Did you get it right? 4 7 Step #4

16 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 twice There is only one cell in the top block where the number 7 can go. Can you find it? Step #5 7

17 17 3 1 Did you get it right? 4 7 7 Step #5

18 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 7 4 7

19 19 3 1 Did you get it right? 4 7 7 7 Step #6

20 20 3 1 Where will the 4 go in this block? 4 7 7 7 Would you like a hint? Step #7

21 21 3 1 4 7 7 7 Step #7

22 22 3 1 Did you get it right? 4 7 7 7 4 Step #7

23 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 24 3 1 Did you get it right? 4 7 7 7 4 4 Step #8

25 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 26 3 1 There is only one cell where the number 3 can go Can you find it? 4 7 7 7 4 4 Step #9

27 27 3 1 Did you get it right? 4 7 7 7 4 4 3 Step #9

28 28 3 1 Where will the number 3 go in the middle block? Would you like a hint? 4 7 7 7 4 4 3 Step #10

29 29 3 1 There is only one possible place for the number 3 in the middle block 4 7 7 7 4 4 3 Step #10

30 30 3 1 Did you get it right? 4 7 7 7 4 4 3 3 Step #10

31 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 4 3 3 Step #11

32 32 3 1 Did you get it right? 4 7 7 7 4 4 3 3 3 Step #11

33 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 4 3 3 3 Step #12

34 34 3 1 There is only one possible cell for the number 2 in the top left block. 4 7 7 7 4 4 3 3 3 Step #12

35 35 3 1 Did you get it right? 4 7 7 7 4 4 3 3 3 2 Step #12

36 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 4 3 3 3 2 Step #13

37 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 4 3 3 3 2 Step #13

38 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 4 3 3 3 2 Step #13

39 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 4 3 3 3 2 2 9 Step #13

40 40 3 1 Where will the 3 go in the top right block? 4 7 7 7 4 4 3 3 3 2 2 9 Step #14 3 Did you get it right?

41 41 3 1 Where will the 5 go in the top left block? 4 7 7 7 4 4 3 3 3 2 2 9 Step #15 3 5 Did you get it right?

42 42 3 1 Where will the 9 go in the top left block? 4 7 7 7 4 4 3 3 3 2 2 9 Step #16 3 5 9 Did you get it right?

43 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 4 3 3 3 2 2 9 Step #17 3 5 9 8 Did you get it right?

44 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 4 3 3 3 2 2 9 Step #18 3 5 9 86

45 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 4 3 3 3 2 2 9 Step #19 3 5 9 86 5

46 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 4 3 3 3 2 2 9 Step #20 3 5 9 86 5

47 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 4 3 3 3 2 2 9 Step #20 3 5 9 86 5 91 Did you get it right? The number 1 will go in the last cell.

48 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 4 3 3 3 2 2 9 Step #21 3 5 9 86 5 91

49 49 3 1 The 2 cannot go in the second column twice, so it must go in the 5 th column 4 7 7 7 4 4 3 3 3 2 2 9 Step #21 3 5 9 86 5 19 The 8 cannot go in the 5 th column, so it must go in the 2 nd column 82

50 50 3 1 Fill in the missing number in this column 4 7 7 7 4 4 3 3 3 2 2 9 Step #22 3 5 9 86 5 19 82 6

51 51 3 1 Fill in the missing number in this column 4 7 7 7 4 4 3 3 3 2 2 9 Step #23 3 5 9 86 5 19 82 6 9

52 52 3 1 Which two numbers are missing in this column? 4 7 7 7 4 4 3 3 3 2 2 9 Step #24 3 5 9 86 5 19 82 6 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 53 3 1 Fill in the missing number in this column 4 7 7 7 4 4 3 3 3 2 2 9 Step #25 3 5 9 86 5 19 82 6 9 2 6 5

54 54 3 1 Fill in the missing number in this block 4 7 7 7 4 4 3 3 3 2 2 9 Step #26 3 5 9 86 5 19 82 6 9 2 6 5 5

55 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 4 3 3 3 2 2 9 Step #27 3 5 9 86 5 19 82 6 9 2 6 5 5 8

56 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 4 3 3 3 2 2 9 Step #28 3 5 9 86 5 19 82 6 9 2 6 5 5 81 What number is left to go in this block? Write it in. 5

57 57 3 1 Which number is left to go in this column? Fill it in. 4 7 7 7 4 4 3 3 3 2 2 9 Step #29 3 5 9 86 5 19 82 6 9 2 6 5 5 81 5 1

58 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 4 3 3 3 2 2 9 Step #30 3 5 9 86 5 19 82 6 9 2 6 5 5 81 5 18 9

59 59 3 1 Which number needs to go in this row? Write it in. 4 7 7 7 4 4 3 3 3 2 2 9 Step #31 3 5 9 86 5 19 82 6 9 2 6 5 5 81 5 18 91

60 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 4 3 3 3 2 2 9 Step #32 3 5 9 86 5 19 82 6 9 2 6 5 5 81 5 18 91 59

61 61 3 1 Fill in the number that is missing in this row. 4 7 7 7 4 4 3 3 3 2 2 9 Step #33 3 5 9 86 5 19 82 6 9 2 6 5 5 81 5 18 91 59 2

62 62 3 1 The 2 and 6 are missing from this row. Where will they go? 4 7 7 7 4 4 3 3 3 2 2 9 Step #34 3 5 9 86 5 19 82 6 9 2 6 5 5 81 5 18 91 59 2 26

63 63 3 1 Fill in the missing numbers in this row. 4 7 7 7 4 4 3 3 3 2 2 9 Step #35 3 5 9 86 5 19 82 6 9 2 6 5 5 81 5 18 91 59 2 26 694 Congratulations on completing a Sudoku puzzle!


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