Mathdoku

It was invented by a Japanese mathematics teacher Tetsuya Miyamoto. The objective is to fill the grid in with the digits 1 through N (where N is the number of rows or columns in the grid) such that:

Each row contains exactly one of each digit.

Each column contains exactly one of each digit.

Each bold-outlined group of cells (block) contains digits which achieve the specified result using the specified mathematical operation: addition (+), subtraction (-), multiplication (×), and division (÷).

The puzzle is also known as Calcudoku or KenDoku