Tutorial for Solving an Easy Suduku Puzzle by Logic

solve
sudoku	step 1 2 3 4 5 6 7 8 9 10 <home

A very easy puzzle to get the idea of how sudoku is solved
© Roger Walker

explanations:-

this is step 7

With 4's in r6 and c6 there is only one place for a 4 in box 5 at c4r4 and the new 4 in c4 together with 4's in c6 and r3 fix the 4 in box 2 at c5r2.

Now the new 4 in box 2 with the 4 in c1 fix the 4 box 1 at c2r1.

Row 4 now has only two numbers missing from 1 to 9 and they are 1 and 6. A 6 cannot be in c6r4 because there is already a 6 in c6 so it must be a 1 and consequently a 6 in the remaining space in box 6 at c7r4 .

There is now only one cell left in box 5 which must be ... what?

c1	c2	c3	c4	c5	c6	c7	c8	c9
4	4	1	5	9	6		3		r1	box 1 2 & 3
3	-box 1- 4	4	4	-box 2- 4	4	9	- box 3	5	r2
8	5	9	7	4	4				r3

9	8	3	4	2	1	6	5	7	r4	box 4 5 & 6
	- box 4	4	8	- box 5 - 7	5		- box 6 9		r5
5		7	?	6	9	1	8		r6

	3	8	1	5		4	6	9	r7	box 7 8 & 9
	- box 7 9	5	6	- box 8			box 9		r8
	6		9	8		5			r9