The case notes
How minimum and maximum cells work
Blue inward-arrow cells are smaller than all orthogonal neighbours. Yellow outward-arrow cells are larger than all orthogonal neighbours. Watch a worked example, then try the idea in a puzzle.
Put it into practice
Yellow: higher · Blue: lower
These coloured cells compare with the cells touching their edges. Yellow arrows point out for a maximum; blue arrows point in for a minimum.
Maximum: above 8 → 9
The yellow cell must be larger than each orthogonal neighbour. Eight sits beside it, so the only digit high enough is nine.
Minimum: below 2 → 1
The blue cell works the other way: it must be smaller than each orthogonal neighbour. Two is beside it, so only one fits below.
Edges decide the extremes
Compare each marked cell with its edge-sharing neighbours. Yellow is higher than them all; blue is lower than them all.
Read the transcript
These coloured cells compare with the cells touching their edges. Yellow arrows point out for a maximum; blue arrows point in for a minimum. The yellow cell must be larger than each orthogonal neighbour. Eight sits beside it, so the only digit high enough is nine. The blue cell works the other way: it must be smaller than each orthogonal neighbour. Two is beside it, so only one fits below. Compare each marked cell with its edge-sharing neighbours. Yellow is higher than them all; blue is lower than them all.
