Normal sudoku rules apply. Digits may not repeat within a cage. Numbers outside the grid are X-Sums clues. They indicate the sum of the first X cells in the row/column from that direction, where X is the first number in that row/column. A double-digit X-Sums clue inside a cage prevents BOTH of its digits from appearing anywhere else in the cage (this does mean 11, 22, 33, and 44 are disallowed as X-Sums clues, as those would repeat digits in a cage). A double-digit X-Sums clue may include zero (10, 20, 30, and 40 are valid X-Sums clues).