32nd notes are exactly twice as fast as 16th notes, and because 16th notes get their name from the fact it takes 16 of them to fill up a bar of 4/4 time, 32nds note being twice as fast, get their name from the fact it takes 32 of them to fill up a 4/4 bar.

So when you divide 32 by 4 beats, you get 8 even counts per beat.

32nd notes have 3 flags falling of the notes, or if they're written next to each other they are joined by 3 beams, like so..