What was going on when I was born?

Edward L. Sadowsky, chairman of the City Council's Finance Committee, has decided not to seek re-election this year, in effect bowing out of public life - though not for long, he predicts - after nearly 24 years in elective office. It took him a long time to reach his decision, and his reasons are many, the Councilman from Beechurst, Queens, said in an interview. Seated in the back of a noisy coffee shop across from City Hall, he spoke about everything from the frustrations of serving in a legislative body that has limited authority and his problems with Democratic political leaders to his plans to run for Mayor in 1989. But, as is often the case in such matters, Mr. Sadowsky ultimately described his unexpected decision - one that is destined to shake up the City Council leadership - in personal terms. ''I am now 56 years old, I've served almost 24 years,'' said the Councilman, ''Many people could say, 'Well, all right, I'm retiring.' But I look at it as kind of a graduation. I want to go on to something else entirely different. As a matter of fact, I'm a little excited by it.''

FOR most taxpayers and tax accountants, this is the day of reckoning. But for Boris Kostelanetz, that day may be three or four years away. At the age of 73, Mr. Kostelanetz is widely regarded as the dean of tax fraud lawyers. His firm, Kostelanetz & Ritholz, is said to be the largest firm in New York specializing in the defense of white-collar crime - or, as Mr. Kostelanetz says, ''commercial disputes'' - and the leading one in the nation in tax cases.

Despite fears among many investors that the American economy may be faltering, most economists remain cheery. They say that although some manufacturers will continue to suffer, the overall economy will continue to grow at a modest pace. ''I really don't think it's faltering,'' said Lawrence Chimerine, chairman of Chase Econometrics, a forecasting company. ''We've been in a slow growth period since last summer, and we get bouncy statistics. One month, when they bounce up, people get exuberant. Next month, they bounce down, and people talk about the economy collapsing. Neither view is right.''

C. Todd Conover has scheduled May 4 as his departure date as Comptroller of the Currency.

The automobile dealership of the future may have taken root on the southeast side of this city by the bay. The San Francisco Autocenter, with models from six different car companies under one roof, has more in common with a beguiling shopping mall than with a traditional car dealership. Customers are free to stroll a central aisle and browse among the Toyota, Datsun, Isuzu, Mazda, Chrysler, Plymouth, Saab and Alfa-Romeo models on display. Within that broad aisle, sales people are forbidden to accost them. The customer can wander into a car-oriented bookstore or pause for coffee in a mezzanine-level lounge. The Autocenter is the creation of Martin L. Swig, who established it two years ago despite some grumbling doubts from the auto companies involved. Mr. Swig consolidated his five franchises and two service shops at this site, and the idea seems to have proved itself. Last year, sales jumped to 4,500 cars from 3,000 before the move.

With the drama at an almost unbearable level, Bryan Trottier scored with 1 minute 8 seconds to play tonight to break a tie, propelling the Islanders to a 6-4 victory over the Washington Capitals and sending their opening round playoff series to a decisive fifth game. But before the night ended, the drama would be still more intense. Billy Smith, the veteran Islander goalie, stopped a penalty shot by Bobby Carpenter of the Capitals that would have tied the score at 5-5 with only 30 seconds remaining, and on that save the Islanders' playoff hopes were preserved. Finally, Mike Bossy scored an empty-net goal with 16 seconds left to cap one of the most theatrical finishes in the Islanders' storied playoff history and set up the deciding game Tuesday at Landover, Md.

The Securities and Exchange Commission will step into a Wall Street crossfire on Tuesday when it considers whether to permit trading in over- the-counter stock options and index options and, if so, who should trade them. The issue has pitted almost all of the nation's stock exchanges and the brokerage community's industry group - the Securities Industry Association - against a host of firms, including Merrill Lynch, First Boston and Paine Webber, as well as the Justice Department. No one seems willing to predict the outcome. Few market regulation issues have drawn such intense and strong reaction from Wall Street, according to Brandon C. Becker, an assistant director in the S.E.C.'s Office of Self- Regulatory Oversight and Market Structure.

Last week was Baker week, at home and abroad. An ocean and a continent away from here in Santa Barbara, President Reagan, in an effort to improve government efficiency, delegated near absolute authority over the domestic economy to his new Treasury Secretary, James A. Baker 3d. He gave the Attorney General, Edwin Meese 3d, similar responsibility for domestic policy. And in Paris, with an offer to lead a conference on improving the behavior of currencies, Mr. Baker captured the agenda of world economic policy as well, for at least a few days and perhaps for much longer.

Peter Hunn is a captive of his dream. Up the swath of torn asphalt that is Joiner Hill Road here, about a mile from the main road, what looks very much like a two-car garage stands alone on a scrubby acre of patchy grass. Inside live Mr. Hunn and his wife, Carolyn, and in a tiny living room, paneled in rec-room knotty pine, is what he calls ''the smallest radio station in America.'' ''I thought I'd like to do like a lot of artisans in the Adirondacks did by bringing their own crafts and businesses here,'' Mr. Hunn said. ''So I did the same thing.''

Bernhard Langer became the first German golfer to win one of the four major tournaments today when he came from four shots off the lead with nine holes to go at Augusta National and won the 49th Masters Tournament by two shots. Curtis Strange, Ray Floyd and Seve Ballesteros tied for second. Strange, the 30-year-old Virginian, had appeared headed for a remarkable comeback. But from the 13th to the 15th Strange, who had an 80 in the first round, fell from a three-shot lead to one shot behind Langer.

The Mets roared on to the best start in their 23-year history yesterday when they completed a sweep of the Cincinnati Reds and won their fifth straight game. And they did it with full star quality: Dwight Gooden pitched a four-hit, 4-0, shutout with 10 strikeouts, and Gary Carter hit his third game-winning home run. At the close of a cold but bracing afternoon before 30,456 fans in Shea Stadium, the Mets packed for Pittsburgh with some shining distinctions: No other Met team had ever been undefeated after five games. No other National League team was undefeated after the opening week this season. No player except Carter hit three game-winning home runs in the new season.

''Let's go for it.'' - Jack C. Burcham, before receiving artificial heart. (B7:2.)