The full logical solve of the hard Shikaku for September 22 to September 28, 2026, 15 × 15. 38 steps, 3 techniques, no guessing. Step through it, or jump to any step below.
Only the 3 in row 15, column 1 can reach row 15, column 2, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 3 in row 13, column 4 can reach row 15, column 4, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 9 in row 14, column 3 can reach row 14, column 2, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 6 in row 13, column 7 can reach row 15, column 8, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 6 in row 13, column 5 can reach row 15, column 6, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 10 in row 13, column 13 can reach row 15, column 14, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 12 in row 12, column 11 can reach row 14, column 10, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 3 in row 15, column 11 can reach row 15, column 12, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 3 in row 13, column 9 can reach row 15, column 9, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 8 in row 12, column 8 can reach row 11, column 9, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 2 in row 14, column 15 can reach row 15, column 15, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 3 in row 11, column 15 can reach row 13, column 15, so its rectangle must cover that cell. Just one of its rectangles does.
Some cells can be reached by only one number. Each such number keeps only the rectangles that cover them, and after a few of these steps the 2 in row 9, column 8 has one rectangle left.
Try each rectangle the 10 in row 1, column 10 could still take. All but one lead to a contradiction, so it takes the one left.
The 2 in row 1, column 15 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
Only the 6 in row 3, column 14 can reach row 3, column 15, so its rectangle must cover that cell. Just one of its rectangles does.
The 8 in row 5, column 15 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
Try each rectangle the 8 in row 1, column 2 could still take. All but one lead to a contradiction, so it takes the one left.
Only the 4 in row 10, column 2 can reach row 11, column 1, so its rectangle must cover that cell. Just one of its rectangles does.
Some cells can be reached by only one number. Each such number keeps only the rectangles that cover them, and after a few of these steps the 6 in row 1, column 6 has one rectangle left.
Only the 9 in row 3, column 3 can reach row 1, column 3, so its rectangle must cover that cell. Just one of its rectangles does.
The 10 in row 7, column 1 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
Only the 6 in row 10, column 4 can reach row 11, column 3, so its rectangle must cover that cell. Just one of its rectangles does.
The 2 in row 12, column 4 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
Only the 4 in row 9, column 7 can reach row 9, column 5, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 10 in row 10, column 10 can reach row 10, column 6, so its rectangle must cover that cell. Just one of its rectangles does.
The 2 in row 9, column 15 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
Some cells can be reached by only one number. Each such number keeps only the rectangles that cover them, and after a few of these steps the 2 in row 2, column 5 has one rectangle left.
Only the 12 in row 4, column 8 can reach row 2, column 6, so its rectangle must cover that cell. Just one of its rectangles does.
The 3 in row 2, column 9 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
The 3 in row 5, column 9 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
Only the 6 in row 5, column 4 can reach row 3, column 5, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 6 in row 3, column 12 can reach row 3, column 10, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 4 in row 6, column 13 can reach row 5, column 12, so its rectangle must cover that cell. Just one of its rectangles does.
The 12 in row 7, column 10 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
The 10 in row 8, column 5 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
The 8 in row 6, column 6 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
The 2 in row 7, column 9 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.