What do 8,700 math teachers, 2,000 fencers, 879 outdoors writers and 2,600 Presbyterians have in common? They all helped make 1990 the best year ever for conventions, says the annual report of the Salt Lake Convention and Visitors Bureau.

Published this week, the report sums up a year in which 5 million visitors came to the city, added $1.2 billion to the economy, provided some 30,500 jobs with a payroll of $420 million . . . and then went home.Despite those record levels, though, don't get the idea that Visitors Bureau President Richard E. Davis is satisfied. He's not.

"The Salt Palace is still our greatest challenge," says Davis in his president's letter. "Because of Salt Palace deficiencies, we have lost over 50 major conventions, worth nearly $100 million."

It's a subject that Davis has been leaning on for several years, so far to no avail, but he hasn't given up.

"We are hopeful that a renovation and expansion project will soon begin and that 1991 will be the year we can begin marketing Salt Palace improvements rather than Salt Palace deficiencies."

That hope may or may not be justified. At this time, funding for an enlarged and renovated Salt Palace is still on the table at the Utah Legislature.

Whatever happens, those record numbers of visitors last year don't sound like a travel industry in trouble, and it isn't. But it could be so much more, says Davis.

The Salt Palace, as it now stands, he said, means the bureau cannot book groups who have major annual banquets; it can't sell to groups who have rapidly growing trade shows and exhibits; it means passing on certain conventions due to a lack of adequate meeting rooms for scientific, technical or medical meetings.

What it does mean, said Davis, is that Salt Lake City, with the existing Salt Palace, must continue to reach for "a smaller market which has less demand for modern convention facilities."

That sounds pretty downbeat, but there are clearly a lot of groups who meet that criteria. Last year the bureau booked 226,177 room-nights in future convention business, a 52 percent increase over its best previous year and a sixfold increase over its average annual bookings prior to its reorganization in 1985.

Still, "with a convention center which can compete with the new and improved centers offered by other cities, we could book business at a much stronger pace," said Davis.

Nevertheless, you work with what you have. Davis said marketing efforts have been redirected and more tightly focused to increase small corporate group bookings - up 135 percent from 16,835 room-nights in 1989 to 39,563 last year.

According to the bureau, the impact of those booked rooms on the Salt Lake economy was $66.49 million, produced from an investment of $2.22 million from transient room taxes passed through the county by visitors staying at member hotels.

In other words, he noted, for each room-tax dollar spent, almost $30 was returned.

In addition to room taxes, the bureau generated income through membership dues, merchandise sales, advertising placed in its publications, grants, contracts and various other services. Private-sector revenues last year were $785,195, a 68 percent increase over 1989.

As noted above, 1990 was the best year Salt Lake City has ever had for conventions. The Salt Palace Convention Center and downtown hotels hosted 19 major citywide conventions, the cream of the 4,996 total groups that held meetings in the city last year.

Davis said that business meant downtown hotels enjoyed near 100 percent occupancy for 92 nights during the year.