The chairman of the House Ways and Means Committee, Rep. Al Ullman (D-Ore.), began numbly, looking for a way out. He was already billions of dollars over his head.

"Some gave me the magic number 111," he murmured. "I'm just trying to see what this is before we proceed."

The last big poker game of the 95th Congress had started. The House and Senate Conference on the huge revenue act of 1978 - 10 members from the House Ways and Means Committee and 14 from Senate Finance - were sitting down to play with a series of bewildering wild cars popping of the deck.

The "magic" item, No. 111 on a voluminous list of House-Senate differences, turned out to have been wrought by Senate Finance Committee Chairman Russell Long (D-La.) - a little Senate amendment instructing the Senate conferees to hold down revenue losses after fiscal 1979 "to an extent that is practical and reasonable." Ullman had no such instructions - and wished he did.

His problem was that the House, by a ratio of almost 2 to 1 on Thursday, had instructed him and the other House conferees to approve me iffy, $142 billion tax cut between 1980 and 1983. The Senate already had adopted it, over Long's protests, earlier in the week.

"If I were in the Democratic leadership, I'd say we'd been snookered," one ways and means staffer said of the House floor vote, which also took the White House by surprise.

Tongue in cheek, Ullman wondered aloud whether it would be "proper" for the House to cave in to fiscal responsibility and back down on the $142 billion tax cut scheme, but no one took him seriously.

The predicament grew worese Thursday night when the House served up still another wild card by refusing to accept tuition tax credit legislation unless it were expanded to include elementary and secondary schools as well as colleges.

At a meeting on that dilemma yesterday morning, Long said he was sure the Senate would refuse to approve a credit for elementary or secondary school tuitions - although he was willing to try anything.

"Sign me up for her crusade," he told his conferees, "But gentlemen" he warned, "we're going to have to camp somewhere because we're a long way from Jerusalem."

Republicans, led by Rep. Barber Conable (R-N.Y.), contended the president was just bluffing. They suggested Carter would sign the tax cut bill after all, even if it contains tuition credits.

Long demurred. "The president doesn't impress me as a poker players," he said.

"Yeh, just a crapshooter," Rep. John J. Duncan (R-Tenn.), interjected irreverently.

"We'll, I would say he doesn't play much poker." Long continued. "He quietly said (at a White House meeting Thursday morning with Long and Ullman) that I'm not going to sign any bill that you put tuition tax credit on . . ." He didn't say it in an arrogant way. He said it like a friend, that that's what he's going to do."

A dreamy-cryed few, such as Rep. Charles A. Vanik (D-Ohio), are beginning to envision the possibility of no tax bill at all.

"Nothing could make me happier," chorfled Vanik, a member of the House conferees but one who has steadily denounced this year's tax cut legislation as a giveaway to big business and the well-to-do. What Congress and the country really leed, Vanik told reporters, is a rule prohibiting passage of tax bills 90 days before elections.

Congressional sources indicated Long and Ullman will try to finesse the $142 billion tax cut scheme, known for short as the Numn amendment, by reducing it to a statement of principles. But Vanik said he didn't think House members would sit still for that.

What is most puzzling about the Numn amendment, however, is the fact that the lawmakers most opposed to it seem equally convinced that it will never work. Why fight it so hard if it is, as opponents contend, "a phony." One Democratic aide pointed to a front-page picture in The Washington Post this week showing Sen. William Roth (R-Del.) and other GOP leaders happily claiming ancestry of the plan and labeling it "Son of Roth-Kemp," which came before it.

"If that isn't sticking it up, I don't know what is," he exclaimed of the photo. "That means we've been sold the Brookly Bridge. It's a matter of pride. I think it's an embarrassment to the Democrats."

Vanik gleefully cited another aspect that might discomfit others: If the scheme ever worked, he said, it would make tax cuts automatic and Congress somewhat inconsequential. "This damn nunn thing eliminates the need for a Congress," he declared. "It'll run itself."