If you had billions of dollars, would you donate almost all of it to charity? Well, that's what Mark Zuckerburg, CEO and founder of Facebook, just said he would do. Zuckerburg and his wife Priscilla Chan promised to give 90% of their Facebook _ to society. Right now that is about $45 billion, and they plan to donate the money to things like science and education. Many billionaires have done similar things. Bill Gates, creator of Microsoft, made The Giving Pledge, an activity in which billionaires promise donate more than half of their wealth to charities. This started in 2010, and now 139 people from 15 countries joined it. But giving back and helping others isn't just for big billionaires. People like Zuckerberg, and Gates may have more to give, but people with less are doing it, too. Especially around the holidays, people want to do their part and give back to people who are less lucky than them. Schools may have food collections where people bring a few food items*, and together they can make a big donation to places like homeless people's homes. People also host special events like concerts of runs to be creative while raising money. Regular people donate whatever they can to US charities like the United Way and the American Red Cross. Then these charities are able to help US communities in different ways like education, health and improving the lives of the poor. These individual* donations come together to make a big difference. Mark Zuckerburg promised to donate  _   .
90% of their Facebook shares to society. half of his wealth to the charities. all of his money to charities 45 billion yuan to society.