The board consists of 81 3x3 squares, Around the perimeter of
this grid are another two sets of 3x3 squares. (Letting you mark
rows columns, blocks and digits usage)
Each can be punched out by your finger. A punched out digit
leaves with a nice popping sound, but is left hanging from
hinge benieth the board.
You can pull the number up, for marking digits that your sure
Turning the board upside down and 1 long movement with the
palm of your hand brings them all back and ready for another
Punchable lines along the borders between the 3x3 squares let
you set it up in non-standard ways.
You can mark the original ones by pulling them up and out a
The app has bubble-wrap on the numbers you punch out, and
when punched out makes that satisfying pop while the number
goes grey and splattered. Long clicking pulls it "up" with a