Casino game that's the basis of this puzzle's theme

Usage examples of twentyone.

They could easily have big establishments whole thing quite painless out of all the taxes give every child born five quid at compound interest up to twentyone five per cent is a hundred shillings and five tiresome pounds multiply by twenty decimal system encourage people to put by money save hundred and ten and a bit twentyone years want to work it out on paper come to a tidy sum more than you think.

She was twentyone, blond, by all odds the best-looking girl within five hundred mites, and her effect on the other unmarried men had been explosive.