What do Elon Musk, Donald Trump and Oprah Winfrey have in common? They're all really, really rich. But do you know their actual net worths?

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Test your knowledge of these three and some other equally as big names. See if you can guess how rich they are.

Jeff Bezos

Amazon began as a small startup run out of Jeff Bezos' Seattle garage in 1994 and has grown into an e-commerce giant worth over $1.5 trillion. Bezos remains the company's CEO and holds a 10.6% stake, Forbes reported.

You may know that Bezos is the richest man in the world, but do you know how much he is actually worth? See what Bezos is worth.

Bill Gates

Bill Gates co-founded Microsoft -- then called Micro-Soft -- with his childhood friend Paul Allen in 1975. He left his daily job at the software company that made him rich in 2008 to focus on charitable pursuits through the Bill and Melinda Gates Foundation. Over the years, he has sold or given away much of his stake in Microsoft -- and with his recent divorce announcement, it seems likely his net worth will go down, but he'll still be very wealthy.

Find out just how rich Gates is.

Joe Biden

President Joe Biden began his political career as a member of his local county council and went onto become one of the youngest people ever elected to the U.S. Senate. He became the 47th vice president under President Barack Obama and was elected in November to become the 46th president of the United States. But despite his long political career, Biden has made most of his money outside of politics.

See President Biden's net worth.

Oprah Winfrey

Oprah Winfrey has turned her earnings and success from her long-running talk show into a veritable media empire. She has her own cable channel, a stake in Weight Watchers and a multi-year deal with Apple to create content for its streaming channel. In 2020, Forbes named her the ninth-richest self-made woman in America.

But just how rich is she? Find out how much Winfrey is worth.

Donald Trump

Former President Donald Trump is the first billionaire president in United States history, Forbes reported. The bulk of his fortune comes from his New York City real estate holdings, but he also brings in money through licensing deals, golf courses and a winery.

See how much Trump is worth.

Elon Musk

The CEO of rocket producer SpaceX and electric car maker Tesla, Elon Musk is changing the way the world moves. He wears many hats, including inventor, executive and futurist -- roles that have paid him well.