It was 24 but you get some zero nic HB or 6 mg and mix the two. You'd end up with either 12 or about 15.
I have some pg and vg nic base at home but I believe they are 36 - so that won't help! I also have some plain PG and VG - not sure if that will help. I haven't DIY'd in quite a while and can't remember how to break it down. I used to have to read the nic supplier's instructions every time I mixed because it was like a brain freeze every time!

As a matter of fact, I need to clear mine.