昨天翻一篇财经的文章，对其中一句感到很困惑：「US$30MM venture capital fund focused on Japan」。当时心想，这句是要写30「百万」吗？怎麼会有两个M？30「百万乘百万」这数字似乎不太合理。
查到一篇文章才长知识了（原文请见文末）。这篇文章谈到，罗马数字的M代表「千」，而MM代表「百万」。所以，该文章确实是指30「百万」。
然後又心想，原来这里的M不是「百万」，那下次看到M不就无法知道这到底是「千」、还是「百万」？刚好这篇文章下面也有提到，很多商业文章会以小写k代表「千」，而以小写m（或小写mn）代表「百万」，因此得解。
整理在下方供参考：
1. 大写M：千
2. 大写MM：百万
3. 小写k：千
4. 小写m/mn：百万
以下为该文章全文：
http://www.accountingcoach.com/blog/what-does-m-and-mm-stand-forWhat does M and MM stand for?
The Roman numeral M is often used to indicate one thousand, and MM is used to indicate one million. For example, an expense of $60,000 might appear as $60M. Sales of $3,000,000 might be written as $3MM. Internet advertisers are familiar with CPM which is the cost per thousand impressions.
In recent years some people began using k to represent one thousand. For example, an annual salary of $60,000 might appear as $60k instead of $60M.
In a recent business publication I saw million represented by mn and also by m (both lower case). This means it is possible for you to see $1,400,000 expressed as $1.4 million or $1.4mn or $1.4m or $1.4MM or $1,400k or $1,400M.