Why does N stand for Knight?

Why does N stand for Knight? N is one letter. K is taken. In Russian, words for king and knight begin with same letter, and we use 2-letter abbreviation (but for the king, and knight is still 1-letter).

N is one letter. K is taken. In Russian, words for king and knight begin with same letter, and we use 2-letter abbreviation (but for the king, and knight is still 1-letter).