From TMZ:

It costs a FORTUNE to feed 23 mouths ... just ask TLC reality star Jim Bob Duggar who took his enormous family out for burgers in NYC yesterday -- and we know exactly how much they spent.

Jim Bob -- along with his wife Michelle and 21 other family members -- hit up Bill's Bar & Burger in Manhattan ... splurging on burgers, shakes, fries, onion rings, you name it.

FYI -- Burgers start at $7.95 and could double in price if you want cheese and/or another burger patty.  Shakes run in the $6 range ... $4 for fries ... $8 for nachos ... $2 per soda.

Buuuuut ... the "19 Kids & Counting" fam did get a nice discount ... 6 of the children qualified for the kids menu -- $7.95 per meal.

... It was $614!!!