Fill in the grid so that every row, every column, and every 3x2 box contains the digits 1 through 3. Each row, column, and 3x2 box contains one 1, two 2's, and three 3's.

Fill in the grid so that every row, every column, and every 3x3 box contains the digits 1 through 3. Each row, column, and 3x3 box contains three 1's, three 2's, and three 3's.

Fill in the grid so that every row, every column, and every marked box contains the digits 1 through 4. Each row, column, and box contains one 1, two 2's, three 3's and four 4's. Orthogonally adjazent cells must have different digits.