The IQ requirements to become a billionaire may not be as high as you might think.

With a fortune of $126 billion, Amazon founder and CEO Jeff Bezos is undoubtedly the richest man in the world, but he may not be the smartest. At least that's what he thought in college.

In the 1980s, Bezos studied physics at Princeton University, according to NBC Business. Despite earning a scholarship, he still didn't think he was smart enough to compete with others. So, Bezos switched from physics to electrical engineering and computer science, starting an amazing life journey.

Such an epiphany came from a math problem. " I couldn't solve the partial differential equation, it was really hard, recalls Bezos. At the time, I was studying with my roommate Joe, who was also very good at math. The two of us spent three hours working on this one assignment and came up empty."

At a loss, Bezos and his roommate eventually turned to friend Yashanta Rajakarunayak for help. "We showed him the problem, and he stared at it for a while and then said 'the answer is cosine.' I was surprised and asked 'that's the answer'. He seemed quite sure and ran the calculations for both of us."

Through three pages of detailed algebraic calculations, the answer that Yashanta eventually came up with was indeed cosine. Bezos asked him if that was what he had just done in his head, and Yasantha replied, "No, that's not possible. Three years ago, I answered a very similar question. When I mapped this problem onto that one, the answer was clear."

At that moment, Bezos suddenly realized that he should have pursued a different career. "That was a very important moment for me, because it was at that moment that I realized I might never be a great theoretical physicist. I began to self-reflect. In most careers, 90 percent of people can contribute. But in theoretical physics, you have to be among the top 50 in the world, or you really can't help much."

He goes on to recall, "I looked around the room and then became acutely aware that there were three people in the class who were much better at physics than I was. For them, physics was much easier. These people's brains are connected differently than ours, and the discovery was astounding."

After that, Bezos turned to electrical engineering and computer science and "dedicated himself to starting and running his own business." In 1994, while working at a hedge fund, Bezos discovered a startling statistic that the Web was growing at a rate of 2,300 percent per year, which inspired him to start Amazon, an online bookstore, in 1995. Today, Amazon's market capitalization is over $1 trillion and Bezos sits as the world's richest man