Walkthrough 1 - Hard

Step 4

			2		9
			1	6			2
2	4	6	5					1
5						3	7
6								2
	8	1			2			9
4				5	1	2	8	7
				4	7
			9	2	8

A bit more complex here. As we can see above the 2s found mean that there can be a 2 in either the top right or bottom right box of section 5. Now if we look at section 4 we can see due to the 2 in box 1 the 2 has to be in the top right group of 4 boxes and due to the 2 in section 6 it has to be in one of the top two boxes (highlighted in yellow). This means the 2 can't be the top right box in section 5 and has to be the bottom right box.

Click here for Step 5