The full logical solve of the hard Shikaku for September 15 to September 21, 2026, 15 × 15. 42 steps, 4 techniques, no guessing. Step through it, or jump to any step below.
The 1 in row 7, column 2 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 1 in row 11, column 12 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 9, column 4 can reach row 8, column 2, so its rectangle must cover that cell. Just one of its rectangles does.
Every rectangle the 8 in row 1, column 13 could take covers the same 2 cells. Other numbers can’t use them, and that leaves the 10 in row 2, column 10 with one rectangle.
The 8 in row 1, column 13 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
Every rectangle the 7 in row 9, column 1 could take covers the same 5 cells. Other numbers can’t use them, and that leaves the 4 in row 15, column 1 with one rectangle.
The 9 in row 15, column 3 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 7 in row 9, column 1 can reach row 13, column 1, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 2 in row 12, column 2 can reach row 13, column 2, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 3 in row 12, column 5 can reach row 12, column 3, so its rectangle must cover that cell. Just one of its rectangles does.
Every rectangle the 9 in row 15, column 9 could take covers the same 8 cells. Other numbers can’t use them, and that leaves the 9 in row 14, column 13 with one rectangle.
Every rectangle the 4 in row 11, column 13 could take covers the same 2 cells. Other numbers can’t use them, and that leaves the 12 in row 10, column 2 with one rectangle.
Only the 6 in row 14, column 7 can reach row 12, column 6, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 9 in row 11, column 10 can reach row 13, column 8, so its rectangle must cover that cell. Just one of its rectangles does.
The 2 in row 14, 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 9 in row 15, column 9 can reach row 15, column 6, so its rectangle must cover that cell. Just one of its rectangles does.
The 2 in row 14, 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.
Only the 3 in row 12, column 11 can reach row 13, column 11, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 4 in row 13, column 15 can reach row 15, column 15, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 8 in row 10, column 15 can reach row 11, column 15, so its rectangle must cover that cell. Just one of its rectangles does.
The 3 in row 3, 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.
Every rectangle the 12 in row 4, column 13 could take covers the same 6 cells. Other numbers can’t use them, and that leaves the 2 in row 3, column 12 with one rectangle.
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 3 in row 3, column 7 has one rectangle left.
The 3 in row 3, 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.
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 12 in row 4, column 13 has one rectangle left.
Only the 4 in row 11, column 13 can reach row 11, column 14, 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 7 in row 6, column 4 has one rectangle left.
Every rectangle the 12 in row 7, column 9 could take covers the same 6 cells. Other numbers can’t use them, and that leaves the 3 in row 7, column 7 with one rectangle.
The 4 in row 9, 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 3 in row 7, 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 2 in row 7, column 3 has only one rectangle left that fits: the right area, inside the grid, clear of other numbers and of the rectangles drawn so far.
Every rectangle the 6 in row 8, column 14 could take covers the same 2 cells. Other numbers can’t use them, and that leaves the 12 in row 7, column 9 with one rectangle.
The 8 in row 9, column 11 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 6 in row 8, column 14 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 4 in row 1, column 1 could still take. All but one lead to a contradiction, so it takes the one left.
The 10 in row 2, 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 6 in row 4, 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.
The 6 in row 3, column 2 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 4 in row 5, 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.
The 2 in row 5, column 3 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 4 in row 5, column 7 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 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.