TWICE a month, at the Sheung Wan Civic Centre or a similar venue, 200 to 300 people gather early in the morning and are driven into a frenzy by an auctioneer selling not land, not gold, but numbers. The figures are vehicle registration numbers, and the auctioneer is employed by the Government to raise money for the Hong Kong Lotteries Fund, a charitable organisation that manages to collect more than $2 million from each auction. Usually sold in lots of 50 at a time, the numbers become available as cars are scrapped, or their owners leave Hong Kong or, in some cases, pass away. Numbers cannot be transferred, but are returned to the Government for reissue. The auctions are open to the public and, according to one senior official with the Government's Vehicle Inspection and Records Section, there are regulars who show up simply to witness the action. The record was set in February this year, when plate number 2 from the Financial Secretary's office was bought for $9.5 million by a property company owner. When the stakes are this high, only the rich can play. Although those attending the auctions are predominantly Chinese, non-Chinese-speakers are also often present, and translators are provided. There are many reasons why a number may be of value. First, as in the case of the ''2'' auctioned in February, is its historical significance. The lower the number, the earlier it would have been issued and the greater its worth. Those prefixed by the letters HK are also considered valuable, because they were the first letter prefixes used. Numbers have always had a special appeal and significance for the Chinese, the official pointed out. ''For Chinese-speaking people, certain numbers are considered valuable because when they are pronounced, they sound similar to words suggesting wealth and well-being,'' he explained. ''For example, in Cantonese, the number eight sounds like the word describing prosperity or riches. Nine sounds like long life or eternity, and three is similar to 'alive'.'' Numbers with multiple eights, nines and threes are sought after and, generally speaking, the more of each the better. Combinations can render more complex meanings, such as 7879. Seven sounds like ''sure'', thus the combination could be taken to mean ''sure to prosper, sure to last long''. Also sought after are numbers which may have personal significance. ''If you know a number has been released and you would like the opportunity to bid for it, you can apply in advance by submitting a form,'' said the official. ''When that number is about to come up for auction, you will be informed.'' But he warned that some people waited for years for a particular number to become available. Notices of the auctions are regularly carried in most local papers.