1. A peremptory challenge is an objection to a prospective juror for which no reason need be assigned. Upon any peremptory challenge, the court must exclude the person challenged from service.

2. Each party must be allowed the following number of peremptory challenges:
(a) Twenty for the regular jurors if the highest crime charged is a class A felony, and two for each alternate juror to be selected.
(b) Fifteen for the regular jurors if the highest crime charged is a class B or class C felony, and two for each alternate juror to be selected.
(c) Ten for the regular jurors in all other cases, and two for each alternate juror to be selected.

I think they're seating 12 + 6 alternates and he's charged with a class E felony so that would be part (c).

That gets you to 22...10 + 12 (for the alternate count).

Typically each side will have an equal number of jurors they can strike for whatever reason.

Any additional jurors beyond that can only be stricken for justified reasons approved by the court.

in this case because the charges are for Class E felonies.