Sudoku no 641 (Easy)

I have been able to create and grade sudoku puzzles in bulk for some time now. However, I have always had to render them in a grid one by one using an online sudoku application. This has restricted me to producing a few puzzles, which I display on this blog.

I recently worked out how to render my puzzles in a standard grid using a Python program, which can then write them out to a PDF file. This should eventually allow me to produce PDF files containing hundreds of sudoku puzzles, which I will offer for sale elsewhere on the Internet.

You can see the first puzzle I created in this way below. Click on the image to enlarge it / bring it into focus if necessary:

Here is the same puzzle in the format I normally use:

Solve online 

Sudoku grader and solver 

See the answer