THAT TRULY conscientious political science graduate student of the late-26th-century, the one with the unhappy assignment of explaining the 1980 presidential election to the class, had best come equipped to the project with a working knowledge of our arithmetic and a functioning sense of humor.

For numbers may tell us and our descendants more about American life in the autumn of 1980 than all the press releases, speeches or (perish the heresy) editorial columns. Take the recent report out of that Disneyland for adults, Las Vegas. A young man in his 20s, having phoned ahead to avoid any cardiac arrest on the part of the management or other customers, arrived at that city's Horseshoe Club with $777,000 in American dollars. This he had converted into 1,554 $500 gambling chips, which he then bet on a single roll of the dice, double or nothing. The unmasked stranger won and, in lieu of elation, did offer an explanation for his adventurous chance-taking: "You know, this damned inflation was just eroding this money," he said. "I figured I might as well double it or lose it."

Granted most of us have not been forced to such dramatic measures, but double-digit inflation over an extended period can certainly alter the way citizens do think about numbers, especially when money is involved. Wednesday night in the Horseshoe Club may tell more, and more eloquently, about the reality of inflation in this society than all the Consumer Price Indexes laid end to end. Inflation will have finally won when such a story is no longer news.

John Anderson saw the ravages of grade inflation take only five days. The League of Women Voters had insisted that, if he managed to draw 15 percent in the public opinion polls, Rep. Anderson would be included in the presidential debates.Mr. Anderson did just that, and he was a participant in the Baltimore debate on Sunday night. No one connected with the League suggested that Mr. Anderson's performance embarrassed, in any way, either the League or Mr. Anderson. In fact, according to one of the keepers of our most important numbers, Louis Harris, Mr. Anderson's share of voter support grew to 19 percent of the electorate after the debate. So what happens? The League of Women Voters drops Mr. Anderson from its early October guest list and invites President Carter to debate former governor Ronald Reagan.

Mr. Anderson and Mr. Carter were, by Mr. Carter's rules and as the nightclub columnists used to put it, "don't invite 'ems." When Mr. Carter refused to come to Baltimore, a debate could still be held between Mr. Reagan and Mr. Anderson. But now, Mr. Reagan -- who, as far as we know, does not have a three-debate deal with Mr. Anderson -- has declined the latest invitation, which leaves the League with Mr. Carter and a reserved auditorium. You can debate with two, or even three, but not with one.

But we can ask that late-26th-century graduate student to tell our story not simply "in mournful numbers." After all, an energetic federal judge has directed the federal government to change the numbers collected in its 1980 billion-dollar census. It seems that the uncounted people must now be counted by a plan rather than by any actual door-to-door canvass. Numbers again, only this time what is involved is $50 billion in annual federal funds and the population formula that determines their allocation as well as how the 435 House seats will be divided up among the 50 states for the next 10 years. The number of House seats determines, in turn, the number of electoral votes each state has in a presidential election. But that will be of interest to the graduate student who has the assignment for the 1984 campaign and its explanation.