Sorry, I misunderstood your question, ignore that reply. I thought you were referring to the the magic number, whether it should be written as words or in digits. - I left the answers in the crossword as they were.
You'll also find that the four central squares and the four corners sahre the same magic as well as any continuous diagonal.
I'm also seeing that pairs of symmetrical 'knight's moves' (i.e., A1,B3,C3,D1 etc) are magic too.