Peter Singer is the Ira W. DeCamp professor of bioethics at Princeton and laureate professor at the Center for Applied Philosophy and Public Ethics at the University of Melbourne. He is the author, most recently, of “The Life You Can Save: Acting Now to End World Poverty.”

They should give some of it away. That's the easy part of the answer, and, according to news reports, the winners already agree with that. The difficult part is: How much, and to whom?

It will do an immense amount of good for people who lost the lottery in a big way.

There is a Web site, "The Life You Can Save," that answers both these questions. (Disclosure: I set it up.) The Web site asks people who have enough to pledge to give some of their income to help people living in extreme poverty in developing countries -- the kind of poverty that is responsible for the deaths of more than seven million children each year.

How much? The proportion of income given should rise according to one's income. Roughly speaking, for income in excess of $10 million per year, I suggest giving away one third. That leaves an ample amount for those lucky enough to have so much.

To whom? These hedge fund managers can benefit from the research done by two former hedge fund managers, who a few years ago left the industry to set up GiveWell, which has raised the bar for rating the effectiveness of charities. As it happens, GiveWell has just released its new ratings for 2011 to 2012. It has two top-rated charities, and six other "standout" charities. Go to the site and pick any of those. That one-third of the lottery winnings will do an immense amount of good for people who lost the lottery in a big way.