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Steve
Joined: 04 Aug 2005 Posts: 3 Location: Leicester
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Posted: Mon Aug 08, 2005 12:09 pm Post subject: Why is it a 9? |
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Code: |
458 .9. 621
.6. 185 ...
.1. 4.. 8.5
879 614 .5.
134 ... 768
625 .3. 914
.86 ..1 ...
.4. 27. .8.
79. ... .3.
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The DRAW function gives the hint R8C6=9. Given that, everything else is easy. But I can't figure out why it should be a 9.
Any ideas? |
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Katie
Joined: 05 Aug 2005 Posts: 13 Location: London
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Posted: Mon Aug 08, 2005 3:32 pm Post subject: |
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Given that R8C6 can be only be a 3, 6, or 9.
If =3, then R8C3=1, R8C1=5 leaving R8C7 with no option, as can only = 1 or 5.
If =6, then R3C6=2, R3C5=6, R5 centre = 5,2,9, R9C4=8, leaving R9C6=6, which impossible.
Thus the only option is 9.
No doubt someone will find a quicker and easier solution to this. |
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bird316 Guest
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Posted: Tue Sep 20, 2005 8:33 am Post subject: Interview |
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So when will w know more [^] |
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chobans
Joined: 21 Aug 2005 Posts: 39
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Posted: Tue Sep 20, 2005 4:23 pm Post subject: |
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I don't know if this is easier but I'll make the solution more logical.
r1c4 and r1c6 both only can be 3 or 7. So you can eliminate 3 and 7 from other cells in box 2(r1c4-r3c6) and get 2 or 6 in r3c6.
row 8: r8c1 - {3,5}, r8c3 - {1,3}, r8c7 - {1,5}.
That makes it a naked triple, so you can eliminate 1,3 and 5 from other cells in row 8. So r8c6 becomes {6,9}.
At this point, you can say r7c4 can only be a 3 since that's the only place in box 8 where 3 can go.
column 6: r3c6 - {2,6}, r5c6 - {2,9}, r8c6 - {6,9}
Again, a naked triple. So you can eliminate 2,6 and 9 from other cells in column 6. So r9c6 becomes 8 after elimination. You'll eventually get a 9 at r8c6 after simple elimination now.
So I guess the system should've given you a 3 at r7c4 first. But since you asked as how you can get a 9 at r8c6... |
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