Military takes the ASVAB which is basically the SAT / IQ Test which qualifies you were certain jobs. For example Nukes in the Navy (which is considered one of the hardest programs for obvious reasons) is 252 score for some combination of scores.

I've worked with at least two such "Nukes". One a researcher, the other a tech startup founder. Both very smart, team-oriented, amiable and down to earth, and inspiring respect (through their ability and how they conduct themselves).

I suppose, on a sub, besides whatever admissions filtering they do for aptitude, you have to take work seriously, and also cooperate and get along with people.

If the ASVAB is basically an IQ test, I’m horrified by how quickly my intelligence has decayed.

When I took it in HS, I scored quite well. I’m almost certain I’m bomb it completely now. Particularly any mathematics I haven’t touched since high school would look foreign to me.