Updated 4:25 p.m. ET

Mark Zuckerberg has come a long way from his Harvard dorm room in 2003, when he started a silly site called FaceMash that was pulled down within days by the university.

Zuckerberg would soon move from FaceMash to the more promising Facebook and would hold on to control as the company skyrocketed in popularity. Still, he probably had no idea that Facebook would become one of the hottest IPOs in history -- or make him so rich.

Facebook priced its IPO late Thursday at $38 a share. Right out of the gate, that made 28-year-old Zuckerberg worth a cool $19.1 billion -- on paper, at least. His worth didn't change that much Friday. Facebook had a wild trading day that saw shares debut at more than $42 but fall in late trading to close at $38.23.

Zuckerberg owns 503.6 million Class B shares and will control nearly 58% of the voting power at the company. (Class B shares are different from the Class A shares being sold to the public in that each Class B share gets 10 shareholder votes.)

Other large Facebook shareholders are also raking in the dough. Dustin Moskovitz, who helped Zuckerberg start the company, is worth nearly $5.1 billion. Another founder, Eduardo Saverin -- whose relocation to tax-friendly Singapore stirred controversy -- is likely worth about $1.4 billion.

Facebook's chief operating officer, Cheryl Sandberg, is worth about $72 million, while chief financial officer David Ebersman is worth about $77 million.

All these huge numbers can start to get overwhelming. Let's put aside Zuckerberg's on-paper wealth for a minute. How much cold, hard cash did he make this week?

Zuckerberg is exercising an outstanding stock option of 60 million shares of Class B stock. He sold 30.2 million of those shares Thursday as Class A shares in the IPO for about $1.15 billion. After the subtraction of what is estimated to be a 1.1% underwriting fee, that leaves him with a bit more than $1.13 billion.

But Uncle Sam is waiting with open arms. Zuckerberg will likely need to pay taxes on the value of all 60 million shares in his stock option (a taxable value of $2.28 billion), and data researcher PrivCo estimates he'll be smacked with a 43% state and federal tax rate. Yowza.

So Zuckerberg can anticipate getting a tax bill of about $980 million, unless his well-paid accountants can find some loopholes. That stuff happens once in a while with the uber-wealthy, I'm told.

At any rate, once the IRS gets its share, Zuckerberg will have an extra $154.6 million in his pocket this week. That can buy a lot of hoodies.

Read more about the Facebook IPO

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• Facebook prices at $38, largest Internet IPO ever
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