THE RELATIVELY bunched-up Democrats did not provide so dramatic a result in Iowa as the Republicans did. What was dramatic and seems worth inspecting is winner Richard Gephardt's surge from 6 percent in a December Iowa poll to his 31 percent victory Monday night. It was fueled by the TV spots he began running Dec. 26. They hit especially hard on the trade issue, and enabled this insider to depict himself as an outsider and scourge of the corporations and to capitalize on the sense of grievance that is so strong in economically ailing Iowa -- never mind that he was importing a planeful of Washington corporate lobbyists to help him at the time. Mr. Gephardt's special success in exploiting this sense of grievance owes a lot to the numbers he's been using in TV spots and stump speeches -- numbers that are, if not downright wrong, then at least misleading.

Number number one is the $48,000 that Mr. Gephardt says a $10,000 Chrysler K-car would cost in South Korea after South Korea's "nine separate taxes and tariffs" are added. Some experts say that $48,000 is much too high, that $29,000 is closer to right. More to the point, eight of the nine surcharges are also imposed on cars produced in South Korea. Mr. Gephardt is right that the Koreans depress the market for U.S.-made cars, but he fails to note that its policy is not just to bar imports but to dampen domestic consumption and encourage savings as part of an overall policy of spurring economic growth by concentrating on exports.

Number number two is the $3,000 that Apple charges for a computer in Japan when the same computer in the United States, says Mr. Gephardt, is priced at $1,500. But it's not quite the same computer. The president of Apple Computer Japan Inc. says much of the difference is due to the cost of adapting the computer to the Japanese language. Also, because of high price levels in Japan, Apple has decided to price its products high for quick profits rather than price them low in the hope of increasing sales.

To the charges that his numbers are wrong, Mr. Gephardt's spokesman replies, "Does anyone want to argue that there isn't such a thing as an unfair trade practice?" No, no one wants to argue that. But the argument over the numbers still underscores what's wrong with the Gephardt trade policy. If high tariff barriers were the only problem, Mr. Gephardt's proposal to raise U.S. barriers unless foreigners' barriers are suddenly lowered could conceivably work. But what he is attacking is more complicated: a set of economic and social arrangements that the East Asian countries have developed to reach long-range goals, and that they're reluctant to change. That reluctance means they might well call Mr. Gephardt's bluff -- which would result in a slowdown in international trade disastrous for everyone.

Mr. Gephardt does admit in speeches and articles that some 80 percent of the trade deficit is the fault not of foreigners' unfair trade practices but of other factors including our own uncompetitiveness. But his 30-second ads and his numbers give the impression that our problems are caused by nefarious foreigners and an unresponsive establishment and that Mr. Gephardt has a quick fix for them. That's a misleading and mischievous impression, and one Mr. Gephardt will regret should this insider-turned-outsider succeed in turning himself into an insider again.