• Elon Musk's mom, Maye Musk, has shared a copy of her son's 1989 computer aptitude test results from the University of Pretoria. 
  • Musk scored an "outstanding" rating, and his mom recalled that he had to take the test twice to verify his high score.
  • The billionaire, who turns 50 later this year, had an early interest in computers.
  • For more stories go to www.BusinessInsider.co.za.

On Wednesday, Maye Musk tweeted her billionaire son's results from a University of Pretoria computer aptitude test of more than three decades ago:

The 17-year old Musk, then a first-year student at the university, scored an A+ for both programming and operating a computer.

It reflects his strong interest in computers. At the age of 12, he sold a simple game called "Blastar" to a computer magazine. Musk described it as "a trivial game … but better than Flappy Bird (a mobile game)."

Shortly after Musk received an "outstanding" rating on his computer aptitude test, he left South Africa for Canada, where he studied for two years at Queen's University in Kingston, Ontario.

He didn't finish his qualification there, instead moving on to the University of Pennsylvania, where he finished two degrees: in physics and economics.

He enrolled for a PhD at Stanford University, but quit after just two days to start a company - Zip2 - with his brother Kimbal. The company provided city travel guides to newspapers.

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Zip2 was bought in a deal worth $341 million, making Musk $22 million.

With some of the money, he started X.com, an online banking company, in 1999. This was merged with another group to form online payment service PayPal.

Musk would eventually earn $165 million from eBay's $1.5 billion takeover deal of PayPal.

In 2002, he founded SpaceX and two years later, he started to invest in the electric car company Tesla Motors, which would eventually see him become the richest person on the planet earlier this year.

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This lasted for a couple of weeks, but at the end of February Tesla's share price slumped, which sent him to second place again - after Amazon's Jeff Bezos.

Musk turns 50 in June this year.

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