Katakana: ナ
Romaji: na
memory aide: think of the knot in the ribbon that you put on a present. This is where the two ribbons, cross. You tie a knot.
Don’t confuse it with オ (romaji: o), the na does nothave the extra line on the bottom.
 Example words:
ナイフ        naifu        knife
ナンãƒãƒ¼ã€€Â  nanbaa     number