How much do billionaires give?
In June, Warren Buffett and Bill and Melinda Gates challenged the nation's billionaires to give away at least half of their net worth. Here's how 9 big spenders dole out their money.
In 2009, the Oracle CEO gave $46.9 million to research age-related diseases and disabilities.
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Last updated December 14 2010: 8:44 PM ET