Barbara Corcoran asks a simple question on 'Shark Tank' to quickly understand if a business partnership will succeed

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Real-estate mogul, investor, and "Shark Tank" star Barbara Corcoran.

• Barbara Corcoran says she loves business partnerships between people with different skill sets.
• When she's trying to figure out if a partnership will work on "Shark Tank," Corcoran simply asks contestants, "What do you do?"
• She said her most successful investments on "Shark Tank" support teams with opposite yet complementary talents.

Barbara Corcoran is known for her extroverted persona and sometimes edgy advice - but one of her most successful business partnerships was with a particularly quiet woman named Esther Kaplan.

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"She's the most conservative person you ever want to meet," Corcoran said at IGNITION, Business Insider's flagship media and technology event. "You almost couldn't even hear her talk. That's how quiet she was in her manner and the way she demonstrated herself."

But Corcoran quickly saw that Kaplan had just about everything Corcoran needed as she built her own business.

"I was able to recognize she was my opposite," Corcoran continued. "She was great at file systems, personnel systems, computers, finance, legal. Everything that I sucked at. And I was great at marketing, recruiting, brainstorming, PR, the bullcrap area of business. And she hated it. So, we were perfect partners."

Read more: 'What the hell were we thinking?': Startup founders who landed a $55,000 deal on 'Shark Tank' nearly missed their big break

Opposites attract, and in Corcoran's case, they helped make for excellent business partnerships. Corcoran has taken that lesson from her real estate mogul days as the founder of The Corcoran Group - which she sold in 2001 for $66 million - to her present role as a judge on reality TV show "Shark Tank."

To figure out if potential investors have that ideal mix of talents, Corcoran simply asks, "What do you do?"

When she asks that deceptively simple question, Corcoran is trying to figure out whether or not the contestants contribute different yet complementary talents to the business.

"You can start to size up as to whether they're compatible partners with opposite skill sets," Corcoran said at IGNITION.

Ultimately, as she's noted previously, Corcoran said her most successful Shark Tank investments have been partnerships - like Cousins Maine Lobster, in which Corcoran invested $15,000 in 2012. Today, the food truck business has restaurants and locales nationwide.

"It's almost like two for the price of one," Corcoran said at IGNITION. "I'm paying the same money, getting the same stock, but I'm getting two great entrepreneurs instead of one. My odds of winning are much better."