HBO Star Abby Ryder Fortson -- Kid Can Count to 20,000 Every Week ... On Her Paychecks!

Pint-sized Abby Ryder Fortson is making tons of dough while tearing up Hollywood … starring in 3 TV shows and making a superhero leap to the big screen.

TMZ has obtained little Abby’s HBO contract for “Togetherness.”

Here’s what the 7-YEAR-OLD is making -- $17,500 per episode for season one and with season two already in production, her pay is jumping up to $20,000 per episode. If the show keeps on rolling along for a 3rd season, she’ll get another 5% bump -- and that's just ONE of her jobs.

Abby's crushing the casting process ... also booking gigs on ABC’s “The Whispers,” Amazon’s “Transparent,” and the Marvel movie “Ant-Man.” We mentioned she's 7, right?

Mom and Dad are working actors too, but at this pace ... Abby will be handing them allowance soon.