Rules
''Inshi no heya'' is played on a square grid, broken into "rooms" by heavier borders. One of every room's dimensions will be a single cell; the length or width of the room varying by room. Each room may run either horizontally or vertically, and has a small number appearing in its upper left corner. The puzzle starts with all the cells empty. The goal is to fill all the cells with nonzero single-digit numbers (1 through n, where n is the length of the grid's edge) such that: *The numbers in each room, when multiplied together, equal the small number in the upper left corner of the room * No number appears twice in a column or rowSolution methods
A usual place to start are single-celled boxes, as these can be filled in trivially. Then, one can look at boxes that have only one combination of numbers that multiply to make the total. These are often prime-numbered boxes, but can also be, for example, a 2-cell 72, which must contain 8 and 9. The "naked pairs" and "hidden pairs" techniques, often used inHistory
''Inshi no heya'' first appeared inSee also
*References