Starting employment in the middle of a pay cycle. I'm not sure if this is the place to ask this question but here goes. 

I've noticed that when I start a job on a non pay day friday the money from that week seems to vanish. In my last 3 jobs my first paycheck is usually for 1 week instead of 2 or 2 weeks instead of 3. The checks continue skipping 1 week, even when I quit I only received money from that last pay period.

What I'm wondering is am I doing the math wrong or is there another way I'm supposed to get that money?