| Junior Puzzle #5 - One Possible Solution Approach… | ||||||||||||
| NB: There is only one final solution to this Sudoku puzzle… | ||||||||||||
| A | B | C | D | E | F | G | H | I | ||||
| 1 | ||||||||||||
| 2 | AA | BB | CC | Reference to 3x3 Blocks AA, BB & CC | ||||||||
| 3 | ||||||||||||
| 4 | ||||||||||||
| 5 | DD | EE | FF | Reference to 3x3 Blocks DD, EE & FF | ||||||||
| 6 | ||||||||||||
| 7 | ||||||||||||
| 8 | GG | HH | II | Reference to 3x3 Blocks GG, HH & II | ||||||||
| 9 | ||||||||||||
| A | B | C | D | E | F | G | H | I | ||||
| 1 | 1 | 2 | 3 | 9 | 8 | 6 | 7 | Junior Puzzle #5 - November 11, 2005 | ||||
| 2 | 7 | 6 | 5 | 4 | 1 | 9 | 2 | Original puzzle as published © joe-ks.com | ||||
| 3 | 9 | 8 | 6 | 2 | 7 | 1 | 4 | |||||
| 4 | 8 | 2 | 4 | 3 | 7 | 6 | 9 | |||||
| 5 | 3 | 9 | 7 | 2 | 4 | 1 | 5 | 8 | ||||
| 6 | 5 | 6 | 1 | 8 | 2 | 4 | 3 | |||||
| 7 | 1 | 4 | 8 | 7 | 2 | 3 | 6 | |||||
| 8 | 2 | 3 | 4 | 5 | 6 | 8 | 1 | |||||
| 9 | 5 | 8 | 9 | 1 | 3 | 4 | 2 | |||||
| A | B | C | D | E | F | G | H | I | ||||
| 1 | 1 | 2 | 3 | 9 | 8 | 6 | 7 | Look for Rows, Columns or Blocks that have 8 #s already… | ||||
| 2 | 7 | 6 | 5 | 4 | 1 | 9 | 2 | Step 1: Complete Row 5: Missing Cell E5 MUST be for #6... | ||||
| 3 | 9 | 8 | 6 | 2 | 7 | 1 | 4 | |||||
| 4 | 8 | 2 | 4 | 3 | 7 | 6 | 9 | |||||
| 5 | 3 | 9 | 7 | 2 | 6 | 4 | 1 | 5 | 8 | |||
| 6 | 5 | 6 | 1 | 8 | 2 | 4 | 3 | |||||
| 7 | 1 | 4 | 8 | 7 | 2 | 3 | 6 | |||||
| 8 | 2 | 3 | 4 | 5 | 6 | 8 | 1 | |||||
| 9 | 5 | 8 | 9 | 1 | 3 | 4 | 2 | |||||
| A | B | C | D | E | F | G | H | I | ||||
| 1 | 1 | 2 | 3 | 9 | 8 | 6 | 7 | Then look for Rows, Columns or Blocks that have 7 #s already: | ||||
| 2 | 7 | 6 | 5 | 4 | 1 | 9 | 2 | Step 2: Column C needs 2 #s: #s 5 & 9… | ||||
| 3 | 9 | 8 | 5 | 6 | 2 | 7 | 1 | 4 | Look at the 2 blank cells (Cells C3 & C7) - and look across | |||
| 4 | 8 | 2 | 4 | 3 | 7 | 6 | 9 | their rows for either a #5 or a #9… | ||||
| 5 | 3 | 9 | 7 | 2 | 6 | 4 | 1 | 5 | 8 | Because #9 is already in Row 3 (@ Cell A3), #9 can't go | ||
| 6 | 5 | 6 | 1 | 8 | 2 | 4 | 3 | in Cell C3: that means that #5 MUST go in Cell C3 … and | ||||
| 7 | 1 | 4 | 9 | 8 | 7 | 2 | 3 | 6 | that leaves only 1 Cell left for #9 - at Cell C7... | |||
| 8 | 2 | 3 | 4 | 5 | 6 | 8 | 1 | |||||
| 9 | 5 | 8 | 9 | 1 | 3 | 4 | 2 | |||||
| A | B | C | D | E | F | G | H | I | ||||
| 1 | 1 | 2 | 3 | 9 | 8 | 6 | 7 | Step 3: now Row 7 needs only one more #... | ||||
| 2 | 7 | 6 | 5 | 4 | 1 | 9 | 2 | #5 MUST go in Cell G7… | ||||
| 3 | 9 | 8 | 5 | 6 | 2 | 7 | 3 | 1 | 4 | |||
| 4 | 8 | 2 | 4 | 3 | 7 | 6 | 9 | Step 4: Row 3 needs only one more #... | ||||
| 5 | 3 | 9 | 7 | 2 | 6 | 4 | 1 | 5 | 8 | #3 MUST go in Cell G3… | ||
| 6 | 5 | 6 | 1 | 8 | 2 | 4 | 3 | |||||
| 7 | 1 | 4 | 9 | 8 | 7 | 2 | 5 | 3 | 6 | |||
| 8 | 2 | 3 | 4 | 5 | 6 | 8 | 1 | |||||
| 9 | 5 | 8 | 9 | 1 | 3 | 4 | 2 | |||||
| A | B | C | D | E | F | G | H | I | ||||
| 1 | 4 | 1 | 2 | 3 | 9 | 8 | 6 | 7 | Step 5: Complete Block AA: need #s 3 & 4… | |||
| 2 | 7 | 3 | 6 | 5 | 4 | 1 | 9 | 2 | #3 can't go in Cell A1 of Block AA (see #3 in Column A @ A5) | |||
| 3 | 9 | 8 | 5 | 6 | 2 | 7 | 3 | 1 | 4 | so #3 MUST go in Cell B2, & therefore #4 MUST go in Cell A1 | ||
| 4 | 8 | 2 | 4 | 3 | 7 | 6 | 9 | |||||
| 5 | 3 | 9 | 7 | 2 | 6 | 4 | 1 | 5 | 8 | |||
| 6 | 5 | 6 | 1 | 8 | 2 | 4 | 3 | |||||
| 7 | 1 | 4 | 9 | 8 | 7 | 2 | 5 | 3 | 6 | |||
| 8 | 2 | 3 | 4 | 5 | 6 | 8 | 1 | |||||
| 9 | 5 | 8 | 9 | 1 | 3 | 4 | 2 | |||||
| A | B | C | D | E | F | G | H | I | ||||
| 1 | 4 | 1 | 2 | 3 | 9 | 8 | 6 | 7 | 5 | Now Rows 1 & 2 only need 1 more # to complete… | ||
| 2 | 7 | 3 | 6 | 5 | 4 | 1 | 9 | 8 | 2 | Step 6: Complete Row 1: #5 MUST go in Cell I1… | ||
| 3 | 9 | 8 | 5 | 6 | 2 | 7 | 3 | 1 | 4 | |||
| 4 | 8 | 2 | 4 | 3 | 7 | 6 | 9 | Step 7: Complete Row 2: #8 MUST go in Cell H2... | ||||
| 5 | 3 | 9 | 7 | 2 | 6 | 4 | 1 | 5 | 8 | |||
| 6 | 5 | 6 | 1 | 8 | 2 | 4 | 3 | |||||
| 7 | 1 | 4 | 9 | 8 | 7 | 2 | 5 | 3 | 6 | |||
| 8 | 2 | 3 | 4 | 5 | 6 | 8 | 1 | |||||
| 9 | 5 | 8 | 9 | 1 | 3 | 4 | 2 | |||||
| A | B | C | D | E | F | G | H | I | ||||
| 1 | 4 | 1 | 2 | 3 | 9 | 8 | 6 | 7 | 5 | Now Columns H & I only need 1 more # to complete… | ||
| 2 | 7 | 3 | 6 | 5 | 4 | 1 | 9 | 8 | 2 | Step 8: Complete Column H: #9 MUST go in Cell H8… | ||
| 3 | 9 | 8 | 5 | 6 | 2 | 7 | 3 | 1 | 4 | |||
| 4 | 8 | 2 | 4 | 3 | 7 | 6 | 9 | Step 9: Complete Column I: #7 MUST go in Cell I9… | ||||
| 5 | 3 | 9 | 7 | 2 | 6 | 4 | 1 | 5 | 8 | |||
| 6 | 5 | 6 | 1 | 8 | 2 | 4 | 3 | |||||
| 7 | 1 | 4 | 9 | 8 | 7 | 2 | 5 | 3 | 6 | |||
| 8 | 2 | 3 | 4 | 5 | 6 | 8 | 9 | 1 | ||||
| 9 | 5 | 8 | 9 | 1 | 3 | 4 | 2 | 7 | ||||
| A | B | C | D | E | F | G | H | I | ||||
| 1 | 4 | 1 | 2 | 3 | 9 | 8 | 6 | 7 | 5 | Now Rows 8 & 9 only need 1 more # to complete… | ||
| 2 | 7 | 3 | 6 | 5 | 4 | 1 | 9 | 8 | 2 | Step 10: Complete Row 8: #7 MUST go in Cell B8… | ||
| 3 | 9 | 8 | 5 | 6 | 2 | 7 | 3 | 1 | 4 | |||
| 4 | 8 | 2 | 4 | 3 | 7 | 6 | 9 | Step 11: Complete Row 9: #6 MUST go in Cell A9... | ||||
| 5 | 3 | 9 | 7 | 2 | 6 | 4 | 1 | 5 | 8 | |||
| 6 | 5 | 6 | 1 | 8 | 2 | 4 | 3 | |||||
| 7 | 1 | 4 | 9 | 8 | 7 | 2 | 5 | 3 | 6 | |||
| 8 | 2 | 7 | 3 | 4 | 5 | 6 | 8 | 9 | 1 | |||
| 9 | 6 | 5 | 8 | 9 | 1 | 3 | 4 | 2 | 7 | |||
| A | B | C | D | E | F | G | H | I | ||||
| 1 | 4 | 1 | 2 | 3 | 9 | 8 | 6 | 7 | 5 | Step 12: Complete Row 4: need #s 1 & 5… | ||
| 2 | 7 | 3 | 6 | 5 | 4 | 1 | 9 | 8 | 2 | #1 can't go in Cell F4 (cf #1 in Column F @ F2), so | ||
| 3 | 9 | 8 | 5 | 6 | 2 | 7 | 3 | 1 | 4 | #1 MUST go in Cell D4, & therefore #5 MUST go in Cell F4 | ||
| 4 | 8 | 2 | 4 | 1 | 3 | 5 | 7 | 6 | 9 | |||
| 5 | 3 | 9 | 7 | 2 | 6 | 4 | 1 | 5 | 8 | |||
| 6 | 5 | 6 | 1 | 8 | 2 | 4 | 3 | |||||
| 7 | 1 | 4 | 9 | 8 | 7 | 2 | 5 | 3 | 6 | |||
| 8 | 2 | 7 | 3 | 4 | 5 | 6 | 8 | 9 | 1 | |||
| 9 | 6 | 5 | 8 | 9 | 1 | 3 | 4 | 2 | 7 | |||
| A | B | C | D | E | F | G | H | I | ||||
| 1 | 4 | 1 | 2 | 3 | 9 | 8 | 6 | 7 | 5 | Step 13: Complete Block EE (& Puzzle): need #s 7 & 9… | ||
| 2 | 7 | 3 | 6 | 5 | 4 | 1 | 9 | 8 | 2 | #9 can't go in Cell D6 (cf #9 in Column D @ D9), so | ||
| 3 | 9 | 8 | 5 | 6 | 2 | 7 | 3 | 1 | 4 | #9 MUST go in Cell F6, & therefore #7 MUST go in Cell D6 | ||
| 4 | 8 | 2 | 4 | 1 | 3 | 5 | 7 | 6 | 9 | |||
| 5 | 3 | 9 | 7 | 2 | 6 | 4 | 1 | 5 | 8 | |||
| 6 | 5 | 6 | 1 | 7 | 8 | 9 | 2 | 4 | 3 | |||
| 7 | 1 | 4 | 9 | 8 | 7 | 2 | 5 | 3 | 6 | |||
| 8 | 2 | 7 | 3 | 4 | 5 | 6 | 8 | 9 | 1 | |||
| 9 | 6 | 5 | 8 | 9 | 1 | 3 | 4 | 2 | 7 | |||
| A | B | C | D | E | F | G | H | I | ||||
| 1 | 4 | 1 | 2 | 3 | 9 | 8 | 6 | 7 | 5 | 45 | Final Proof: | |
| 2 | 7 | 3 | 6 | 5 | 4 | 1 | 9 | 8 | 2 | 45 | - All Rows add up to 45; | |
| 3 | 9 | 8 | 5 | 6 | 2 | 7 | 3 | 1 | 4 | 45 | ||
| 4 | 8 | 2 | 4 | 1 | 3 | 5 | 7 | 6 | 9 | 45 | ||
| 5 | 3 | 9 | 7 | 2 | 6 | 4 | 1 | 5 | 8 | 45 | ||
| 6 | 5 | 6 | 1 | 7 | 8 | 9 | 2 | 4 | 3 | 45 | ||
| 7 | 1 | 4 | 9 | 8 | 7 | 2 | 5 | 3 | 6 | 45 | ||
| 8 | 2 | 7 | 3 | 4 | 5 | 6 | 8 | 9 | 1 | 45 | ||
| 9 | 6 | 5 | 8 | 9 | 1 | 3 | 4 | 2 | 7 | 45 | ||
| 45 | 45 | 45 | 45 | 45 | 45 | 45 | 45 | 45 | - All Columns add up to 45; | |||
| 45 | 45 | 45 | - All 3x3 Blocks add up to 45… | |||||||||
| 45 | 45 | 45 | ||||||||||
| 45 | 45 | 45 | ||||||||||
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