Would you believe that 20,013,741 copies of the Better Homes and Gardens New Cookbook have rolled off the press so far? That's more than any other hardback except the Bible and some dictionaries.

Counting frantically, someone at Meredith Corp., the publisher, snatched the 20 millionth copy out of the stack and yesterday presented it to the Library of Congress.

And there, said Leonard N. Beck of the Rare Book Division, the red-and-white checked volume will surely feel in good company, for the library has one of the greatest collections of cookbooks in the world.

Now, cookbooks come and go. But this one is so famous that we bet you know the tablecloth patterned cover even if you didn't know its name.

"It started in the Depression, in 1930," said Doris Eby, food editor for Better Homes and Gardens. "Originally it was a premium with the magazine. You got it for $1 with two two-year subscriptions."

A year later it made the best-seller lists, and in 1941 it went on the retail market by itself. That was the year a couple of editors, coming back from a department store lunch, spotted the bolt of red-checked gingham on the fabric counter, bought a yard of the stuff and wrapped the book in it.

This must be the most famous square of gingham anywhere. Certainly it is now an officially hallowed swatch of Americana, which is okay, because the changes in that cookbook over the last 48 years are the changes in America.

"A lot of our early readers were rural," Eby said, "and in fact Meredith's first publication was a magazine called Successful Farming. You won't find Beef Wellington in those early editions -- they didn't have expensive cuts of meat in the Depression." We got hold, not of a first edition, but a 1942 version, its cover brown with age and gravy, its back worn clean off, its pages wrinkled and stained where generations of measuring cups were placed on it.

The index has 13 entries under "Beef." The new edition has 66, including Stroganoff, Fondue, Sauerbraten and Teriyaki. The new book also has a whole section on appliance cooking, which means electric skillets, microwaves, pressure pans and slow crockery. In 1942 the only mechanical tool housewives were expected to have was a hand eggbeater.

"You forget how unsophisticated American cooking was just a few years ago," Eby said. "As late as '65 there was no wine in the recipes. We thought it was daring even to suggest cooking wines. Now there's a wine selection guide."

And a section on freezing. And a section on the metric system. And a section on herbs.

The looseleaf binding, however, is the same as always, plus the page tabs and sleek color photos and the businesslike approach that pares words like a dieter's calories.

One thing's for sure: It's more to the point than the first known cookbook, written in a fine Italian hand by master chef Martino in 1450 and displayed in the library's rare book room.

Now, this is some cookbook, make no mistake. For one thing, it is in great shape physically. As Beck remarked, "There's so much rag in the paper, you could make a shirt from it and wear it."

On the other hand, Martino never does mention quantities of ingredients. And it doesn't even have spaghetti in it. Spaghetti wasn't invented yet.