In an earlier question (Can a standard Sudoku puzzle contain a miniature Sudoku puzzle?), I asked whether a miniature 4x4 Sudoku could be embedded in a standard 9x9 Sudoku.
Inspired by the following comment on that question by quarague:
Looking at this I would guess that it is possible to put a 4x4-sudoku inside a giant 16x16 sudoku. The check would work the same way but it seems like you have enough degrees of freedom to fill everything.
I ask a new question:
In the following grid, can you fill each empty square with a number (1,2,3,...,16) so that there are no duplicated numbers in any row, column or 4x4 block.
I realize that if filling the grid is possible, it can be filled in many ways.