The full logical solve of the hard Shikaku for September 29 to October 5, 2026, 15 × 15. 41 steps, 4 techniques, no guessing. Step through it, or jump to any step below.
The 12 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 3 in row 8, 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.
Only the 2 in row 5, column 1 can reach row 4, column 1, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 3 in row 8, column 1 can reach row 6, column 1, so its rectangle must cover that cell. Just one of its rectangles does.
Every rectangle the 12 in row 13, column 8 could take covers the same 8 cells. Other numbers can’t use them, and that leaves the 10 in row 14, column 10 with one rectangle.
The 2 in row 15, 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 13, column 8 could take covers the same 8 cells. Other numbers can’t use them, and that leaves the 9 in row 15, column 5 with one rectangle.
The 12 in row 13, column 8 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 13, column 2 can reach row 14, column 1, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 3 in row 13, column 3 can reach row 14, column 3, 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 4 in row 9, column 3 has one rectangle left.
Only the 6 in row 10, column 2 can reach row 10, column 1, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 4 in row 10, column 6 can reach row 10, column 4, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 2 in row 12, column 4 can reach row 11, column 4, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 3 in row 11, column 7 can reach row 11, column 5, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 6 in row 12, column 8 can reach row 12, column 5, so its rectangle must cover that cell. Just one of its rectangles does.
The 4 in row 13, 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.
Try each rectangle the 2 in row 1, column 1 could still take. All but one lead to a contradiction, so it takes the one left.
Working through which numbers reach each cell, and the cells every option of a number shares, the 8 in row 1, column 7 is left with one rectangle.
Try each rectangle the 3 in row 1, column 13 could still take. All but one lead to a contradiction, so it takes the one left.
Only the 6 in row 3, column 11 can reach row 1, column 12, so its rectangle must cover that cell. Just one of its rectangles does.
The 6 in row 3, 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.
Only the 3 in row 3, column 15 can reach row 2, column 15, so its rectangle must cover that cell. Just one of its rectangles does.
Every rectangle the 8 in row 4, column 12 could take covers the same 4 cells. Other numbers can’t use them, and that leaves the 9 in row 5, column 14 with one rectangle.
Try each rectangle the 8 in row 2, column 6 could still take. All but one lead to a contradiction, so it takes the one left.
Only the 4 in row 2, column 9 can reach row 2, column 10, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 4 in row 3, column 2 can reach row 3, column 1, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 3 in row 4, column 5 can reach row 3, column 5, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 3 in row 4, column 6 can reach row 3, column 6, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 6 in row 3, column 8 can reach row 3, column 7, 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 8 in row 4, column 12 has one rectangle left.
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 10 in row 6, column 9 has one rectangle left.
Only the 6 in row 7, column 5 can reach row 6, column 7, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 6 in row 9, column 7 can reach row 8, column 5, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 6 in row 9, column 10 can reach row 8, column 8, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 3 in row 8, column 12 can reach row 8, column 11, so its rectangle must cover that cell. Just one of its rectangles does.
Only the 6 in row 9, column 15 can reach row 8, column 14, so its rectangle must cover that cell. Just one of its rectangles does.
The 12 in row 10, 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 11, 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 4 in row 11, 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.
The 2 in row 13, 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.