Normal sudoku rules apply (ie place the digits 1 to 6, once each, into each row, column and rectangular box). One cell in each row, column, and box is a ‘doubler’, and each digit is doubled once. Digits do not repeat in cages. Each cage sums to a different total (with doubled digits counting as twice their value) and the totals are ranked in order from lowest (1) to highest (6). The number in the top left of the cage, if given, indicates this rank.