1. Rows and columns (lines) may not contain duplicate digits, or 0.
  2. Consecutive numbers should be read as decimal numbers.
  3. 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.
  4. Lines may be denoted by the result of the above operation.
  5. To input digits, use numeric keys 1-9. For pencil markings, use shift+[1-9].