By Philip Elmer-DeWitt

    It's tempting to multiply China's 700 million mobile phone users by a percentage pulled out of a hat, and now that China Unicom has announced its deal with Apple (AAPL), everybody seems to be doing it.

    Result: Published estimates of how many iPhones Apple will sell in China next year that range from a low of 1 million to a high of 14 million. Here are the numbers we've seen:

    • UBS analyst Maynard Um: 1 million in fiscal 2010

    • Sanford Bernstein's Toni Sacconaghi: 2.9 million by end of 2011

    • Standard & Poor’s Clyde Montevirgen: 4 million in calendar 2010

    • Susquehana Financial's Jeffrey Fidicaro: 2 million to 5 million

    • Broadpoint AmTech's Brian Marshall: 5 million to 7 million in 2010

    • iPhonAsia's Dan Butterfield: 14 million in the first year of sales

    Everybody's guessing, of course, since China Unicom hasn't even announced its pricing or its terms. Meanwhile, Susquehana's Fidicaro offers investors this handy formula: For every additional 1 million phones Apple sells next year, you can add 18 to 20 cents to the company's earnings per share.

    The Street currently expects Apple to earn $5.84 a share in fiscal 2009 and $6.79 a share in 2010, according to Thomson Financial.