Seven days a week, by 4 p.m., the lines in front of the chattering machines are eight to 10 deep with working-class people clutching small slips of paper. The lines crawl like Saturday at the supermarket until the machine closes at precisely 7:25, when the daily Maryland Lottery number is selected.

On line, some stare into space before making a hurried scribble on the paper and folding it. Others peer into "dream books," cheap paper pamphlets that tell readers how to translate dreams or hunches into a number, in the hope that "Sneaky Pete," "Grandpa" or the "Three Wise Men" will give them the three digits that will turn $1 into $500.

They don't talk much until they reach the machine and and surrender $1, $10 or $100 for some gold-colored tickets to dream on for the next day. Only then will a few belly up to the counter of the liquor or convenience store-cum-betting parlor and order half a pint of an obscure brand of whiskey, or a few cans of beer and some ribs, before returning to a waiting car on Rhode Island Avenue in Mount Rainier.

Atlantic City has its boardwalk; Las Vegas has its glittering strip. Prince George's County has three blocks on Rhode Island Avenue in Mount Rainier, a "border town" just over the District line that sells nearly 3 percent of all the lottery tickets in the state, with a booming liquor and carryout food business on the side.

Like similar outlets bordering Washington in places such as Oxon Hill, Capital Heights, Chillum and even Silver Spring, which together take in about 20 percent of the annual $354 million haul in daily lottery receipts, Mount Rainier owes its good fortune to the fact that the District has no lottery -- yet.

Congress this week upheld Washington's referendum vote in favor of introducing a D.C. lottery, and the District game is expected to appear by the spring of 1982, drawing away an estimated $66 million in Maryland revenues.

Meanwhile the party along the Mount Rainier strip -- two takeouts, three convenience and four liquor stores -- goes on.

"Since I've been here, it's been tremendous," said the manager of Abdallah's convenience store. "Party Time (Liquors) has their crowd, Bass's (Liquors) has their and we have ours. Six in the morning to 11 at night, that's how the lottery goes."

The lottery is actually two games, a one-dollar ticket with a set number on it that is drawn weekly like a raffle, and the far more popular "pick it game," which allows the bettor to choose two or three numbers and bet that the digits will "come out" when the numbers are selected in a Baltimore television studio each evening. A straight bet, a specific three-digit number, pays $500 for every one bet, but is is possible to play various permutations of the three digits on the same bet for a smaller payoff.

The chances of winning a straight bet, however, are one in 1,000, half the payoff rate and less than the 700-to-1 in the illegal street numbers. Still, one government worker, who said she couldn't play the illegal game in good conscience, finds it worthwhile to take an extra bus to Mount Rainier after work a few times a week before going home to Northeast Washington.

"You work from payday to payday, you've got to get lucky in between," said the woman.

She said she never drops more than $10 or $15 a week, and is careful to save enough to pay her bills.

A waiter from a downtown Washington hotel also said he took care of his obligations, but has spent $100 to $200 per week since 1976, when the daily lottery game began.

"When you do waiter work you have extra money. They (his family) don't know that I have this money. I take care of my family. I have the opportunity to spend my money the way I want to , married or not," he said.

He plays at Bass's Liquors, about 20 yards across Eastern Avenue from Washington, because, "they usually have more money on hand here." Like most of the vendors on the strip, Bass's pays off winning tickets in cash.

They make only a nickel on every lottery dollar, about $1,000 a week before they pay two full-time "lottery girls," who run the machine. But they make about 50 percent profit on the 400 pounds of ribs sold daily, and 25 percent on the liquor.

Said owner Aaron Borak, "We render a service. We sell a lottery ticket, something to eat, something to drink. We kid around with 'em a little; they like us and they come back."

By 7:15 the people in construction boots, double-knit and corduroy pants, denim jackets and few knit caps grow edgy in the long line before Bass's machine. At 7:20 the last five or so give up on placing their bets, five minutes before the day's wagering would end, because Reg Mercer has used up the time to buy $40 worth of tickets.

Five minutes later 779 came in and Mercer, a gregarious, small entrepreneur from Northeast Washington, had lost $40.

The day before he had bet $56 and before that $155. He lost that money too, but earlier in the same week he hit for $1,000.

For every 999 losers there is a winner. Joe Cummings, also of Northeast Washington, came in about 20 minutes later with his friend James L. Mourning to pick up 25 not-so-new $20 bills.

"I hit about every two or three weeks," said Cummings, who plays 50 a week. "But hell, I'm behind, and if I was ahead I'd still be playing," he said. "Things are so high, and the way Reagan's doing, I have to do something. This will come in handy for my food bill."

Cummings bought his friends a big bottle of wine and two packs of cigarettes with one of the twenties and walked out into the dark street.