I'm going to repeat the info at the top of Sudoku #1, just in
case you haven't seen that one yet.
I've been doing Sudoku
for a while.There are a lot of people
like me who have figured out some tricks or techniques that help them
complete the puzzles.This page is not
really for them.I met a woman
recently who was just starting to try to do Sudoku.This page is for people like her.I'm not saying that I know every single
trick, but I know enough to complete most puzzles.
The basic rules of
Sudoku are that there is only one of each number in each row, column, and 9
square grid.There isn't any
mathematics or arithmetic.If you know
how to count from 1 to 9, then you can do these puzzles.All of the techniques are based on this
rule.
Here is a sample Sudoku
puzzle.
3
1
7
8
1
9
4
9
6
6
9
8
7
6
5
4
1
1
5
9
2
6
8
3
5
2
This is a Evil
difficulty puzzle (harder than Hard), and it will allow me to show some
examples of a few of the tricks that I've uncovered.I've added the letters below to the rows
and columns in order to talk about each of the 81 squares.As a convention, I will talk about squares
and boxes.There are 81 squares, but
there are 9 boxes of 9 squares.
A
3
1
7
8
B
1
9
C
4
9
6
D
6
9
8
E
7
6
F
5
4
1
G
1
5
9
H
2
6
I
8
3
5
2
J
K
L
M
N
O
P
Q
R
There is a 9 in AL
(because of CM and BQ).There is a 5
in HL (because of GO and IQ).There is
a 6 in FO (because of DJ, EQ, and HM) and another 6 in AN (because of CR and
HM).
A
3
1
9
6
7
8
B
1
9
C
4
9
6
D
6
9
8
E
7
6
F
5
4
6
1
G
1
5
9
H
2
5
6
I
8
3
5
2
J
K
L
M
N
O
P
Q
R
There has to be a 4 in either
AM or BM (because of CJ and FN).There
has to be a 4 or 9 in HO and IO (because of the 4 in AM-BM and FN, and
because of the 9s in CM and DN).There's
an 8 and 9 in EJ and FK (because of AL, DN, DR, and IL).
A
3
1
9
6
7
8
B
1
9
C
4
9
6
D
6
9
8
E
89
7
6
F
5
89
4
6
1
G
1
5
9
H
2
5
6
49
I
8
3
49
5
2
J
K
L
M
N
O
P
Q
R
There's a 2 in BJ
(because of HK).So there is a 5 or 8
in BK and CK (because of HL and IL).That means that there is an 8 in EJ and a 9 in FK.And there's a 6 and 7 in BL and CL, which
means there is a 6 in BL (because of CR) and a 7 in CL.The missing numbers in column J are the 7
and 9.
A
3
1
9
6
7
8
B
2
58
6
1
9
C
4
58
7
9
6
D
6
9
8
E
8
7
6
F
5
9
4
6
1
G
1
5
9
H
79
2
5
6
49
I
79
8
3
49
5
2
J
K
L
M
N
O
P
Q
R
There is a 9 in EP
(because of FK, DN, and GR).There's
an 8 in FM (because of DR and EJ) and another one in CO (because of FM).That means there is an 8 in BK and a 5 in
CK.There's a 2 and a 3 in DO and
EO.There's a 7 in DM (because of AO
and EK).
A
3
1
9
6
7
8
B
2
8
6
1
9
C
4
5
7
9
8
6
D
6
7
9
23
8
E
8
7
23
9
6
F
5
9
8
4
6
1
G
1
5
9
H
79
2
5
6
49
I
79
8
3
49
5
2
J
K
L
M
N
O
P
Q
R
There's a 1 and a 5 in EM
and EN.Therefore, there's a 5 in DP
(because of EM/EN, FJ, and IQ), and there's a 1 in DL (because of EM/EN, FR,
and AK).
A
3
1
9
6
7
8
B
2
8
6
1
9
C
4
5
7
9
8
6
D
6
1
7
9
23
5
8
E
8
7
15
15
23
9
6
F
5
9
8
4
6
1
G
1
5
9
H
79
2
5
6
49
I
79
8
3
49
5
2
J
K
L
M
N
O
P
Q
R
The numbers missing from
box GM-IO are 1, 2, 7, 8.There is a 1
in GJ and a 7 and 8 in column M, so there has to be a 2 in GM.That means that there has to be a 2 in CN
(because of GM and DO/EO) and another 2 in AQ (because of IR, BJ, and CN).
A
3
1
9
6
7
8
2
B
2
8
6
1
9
C
4
5
7
9
2
8
6
D
6
1
7
9
23
5
8
E
8
7
15
15
23
9
6
F
5
9
8
4
6
1
G
1
2
5
9
H
79
2
5
6
49
I
79
8
3
49
5
2
J
K
L
M
N
O
P
Q
R
There's a 3 in BN
(because of AJ and IM).That means
that there is a 4 and a 5 in AM and BM -- and AR, which means EM has to be a
1 and EN has to be a 5.
A
3
1
9
45
6
7
8
2
45
B
2
8
6
45
3
1
9
C
4
5
7
9
2
8
6
D
6
1
7
9
23
5
8
E
8
7
1
5
23
9
6
F
5
9
8
4
6
1
G
1
2
5
9
H
79
2
5
6
49
I
79
8
3
49
5
2
J
K
L
M
N
O
P
Q
R
The numbers missing from
row D are the 2, 3, and 4, but there is a 2 in HK and AQ, so the 2 has to be
in DO -- which means the 3 is in EO.There's another 2 in FP (because of IR and AQ).So there is a 2 in EL and a 4 in ER.That means there is a 4 in DK, a 3 in DQ, a
4 in ER, a 7 in FQ, a 3 in FL, and a 4 in GL.
A
3
1
9
45
6
7
8
2
45
B
2
8
6
45
3
1
9
C
4
5
7
9
2
8
6
D
6
4
1
7
9
2
5
3
8
E
8
7
2
1
5
3
9
6
4
F
5
9
3
8
4
6
2
7
1
G
1
4
2
5
9
H
79
2
5
6
49
I
79
8
3
49
5
2
J
K
L
M
N
O
P
Q
R
Wow!There is a 3 in IM, so a 3 has to be in
GK.That means a 6 is in IK, which
means a 6 is in GP (because of HM and EQ).
A
3
1
9
45
6
7
8
2
45
B
2
8
6
45
3
1
9
C
4
5
7
9
2
8
6
D
6
4
1
7
9
2
5
3
8
E
8
7
2
1
5
3
9
6
4
F
5
9
3
8
4
6
2
7
1
G
1
3
4
2
5
6
9
H
79
2
5
6
49
I
79
6
8
3
49
5
2
J
K
L
M
N
O
P
Q
R
There's a 4 in ER, so
there has to be a 5 in AR, a 4 in AM, and a 5 in BM.There is a 5 in BP (because of CJ and ER),
so there is a 7 in BR and a 3 in HR.
A
3
1
9
4
6
7
8
2
5
B
2
8
6
5
3
1
4
9
7
C
4
5
7
9
2
8
6
D
6
4
1
7
9
2
5
3
8
E
8
7
2
1
5
3
9
6
4
F
5
9
3
8
4
6
2
7
1
G
1
3
4
2
5
6
9
H
79
2
5
6
49
3
I
79
6
8
3
49
5
2
J
K
L
M
N
O
P
Q
R
There is a 3 in CP
(because of DQ) and a 1 in CQ.There's
a 7 in GN (because of FQ), an 8 in GQ, and a 4 in HQ.That means there is a 4 in IO, a 9 in HO, a
7 in HJ, and a 9 in IJ.
A
3
1
9
4
6
7
8
2
5
B
2
8
6
5
3
1
4
9
7
C
4
5
7
9
2
8
3
1
6
D
6
4
1
7
9
2
5
3
8
E
8
7
2
1
5
3
9
6
4
F
5
9
3
8
4
6
2
7
1
G
1
3
4
2
7
5
6
8
9
H
7
2
5
6
9
4
3
I
9
6
8
3
4
5
2
J
K
L
M
N
O
P
Q
R
That means there is a 7
in IP, a 1 in HP, a 1 in IN, and an 8 in HN.