Walkthrough 1 - Hard

Step 1

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

We can see that due to the 2s that are already filled in there is only one square in section 3 where the2 can go.

Click here for Step 2