Normal sudoku rules apply. Digits must sum to the small clue in the top left corner of their cage. Digits cannot repeat within cages. In addition, all cages contain a standard arrow clue, which is hidden. [In an arrow clue, cells along the arrow must sum to the digit in the cirlce from the arrow emerges.] The 'circle' part of the arrow will be at one end of the cage with the arrow extending along the cage to the other end. The arrow must fill the entire cage. The circle may be any number of digits, and multi-digit totals are read in the direction of the arrow.