Contained within the grid are nine non-overlapping 3x3 square regions, which must be located. Each region contains the digits 1-9 once each such that no digit repeats in any row or column. Cells outside regions do not contain digits. Along the line, each time the line passes through a region, the sum of the digits on that pass sum to the same value. If the line passes through a region multiple times, each pass is summed separately.