Holes

The 1-Hole and 2-Hole

It is very handy to know the 1-Hole and 2-Hole, not only because of how common they are, but because of how much space they can sometimes let you clear. The first bonus follow-on to watch for is, if the middle green square matches the number in the gap, then you can clear the yellow squares too:















It gets even better. For both the 1-hole and 2-hole, if the numbers in the question-marked squares are equal, then you can also clear these green squares. This works on both sides of the hole: