Knot Count

Each day has five cords, the same for everyone.
To read a cord, tap the number its knots show.
To tie a number, tap a place on the cord to tie a knot there, and the − beside it to untie one. Then press Check.
The last cord is a top cord: tie the sum of the three cords below it.
Earlier days stay open: use the arrows beside the date.

With a keyboard, Tab to a place on the cord; arrow up ties a knot and arrow down unties one.

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