The No. 1 piece of money advice from a 12-year-old CEO who’s been on ‘Shark Tank’

Mikaila Ulmer, founder and CEO of Me & the Bees Lemonade.
Photo by Jim Bennett

Mikaila Ulmer is 12 and she already runs her own successful business.

She is the founder and CEO of the Austin-based Me & the Bees Lemonade, which is sold in 20 states and carried in Whole Foods markets. In 2016, Ulmer's company sold 300,000 bottles of lemonade. Along the way, Ulmer won a spot on ABC's hit reality show 'Shark Tank,' and she was offered an investment from The People's Shark, Daymond John.

Ulmer's best money advice is to automate your finances.

"I am a Generation-Z kid and I love technology. I would say, track your numbers through a piece of technology, whether it's a laptop or a phone that you can pull out whenever you need to," Ulmer tells CNBC.

In particular, Ulmer recommends using an online tool so that you can share spreadsheets with team members. That's a simple way to allow team members to access the data.

The 12-year-old CEO gets financial guidance from her father.

He tells her repeatedly that "you always have to know your numbers," she says.

Ulmer's dad also taught her to put together a budget, listing her expenses and estimating her income.

Unsurprisingly, Ulmer's middle school buddies ask her for money tips, and she helps them brainstorm business ideas. "We love to come up with different ideas to make money or different ways to solve a problem," says Ulmer. She advises her friends on production runs, pricing and profit margins.

Ulmer may have another business in her near future: Consultant.

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Disclosure: CNBC owns the exclusive off-network cable rights to "Shark Tank."