- Rows and columns (lines) may not contain duplicate digits, or 0.
- Consecutive numbers should be read as decimal numbers.
- Filled cells represent separators, and may contain operation symbols.
- The default operation is addition.
- Precedence rules are respected, i.e. multiplication is always executed before addition.
- Multiple separators are collapsed into one.
- Lines may be denoted by the result of the above operation.
To input digits, use numeric keys 1-9. For pencil markings, use shift+[1-9].