These are Samurai sudoku grids and are quite challenging. Samurai puzzles are constructed from multiple Sudoku grids. In these two examples five 9×9 grids which overlap at the corner regions form the shape of a quincunx that in Japan is called a Gattai 5 (meaning 'five merged') and in the west it is commonly referred to as Samurai Sudoku.
CLICK ON THE SODOKU PUZZLE THAT TAKES YOUR FANCY AND IT WILL OPEN LARGE - THEN PRINT!