I'm sorry I have to admit my age here and ask a question

how can you score below a 21 on the ASVAB? I joined the USMC back in the late 1980's straight out of high school. My ASVAB score was 89 and I took it just because it got me out of class for half a day. I had no real intention of enlisting at that time. I enlisted in the Corps as a 1345 thats engineer mechanical operator and went to boot as an E2 the entire time I was there I got paid more than the 0300 grunts. Even they had to score higher than 21 to join the Marines. I am fairly sure you get 17 points just for writing your name on the top of the form and extra points if you don't eat the crayon. It wasn't my flavor so I returned it when I was done. I like grape, and it was red.