ABOUT 23 MILLION businesses operate in the United States, and only 15,000 have value over $100 million, says Dileep Rao, author of the new book “Bootstrap to Billions: Proven Rules from Entrepreneurs who Built Great Companies from Scratch.” He profiles 28 of what he calls the wealth-creating legends, detailing how the Minnesota-heavy lineup built their companies into engines of job creation. In January, Rao presented nine of those entrepreneurs at the Gary S.

Holmes Center for Entrepreneurship at the Carlson School of Management, University of Minnesota, where he is also an instructor, and then added his own lessons learned. Here are excerpts from each.

Mark Knudson, Venturi Group, who built three medical ventures with a combined valuation of $250 million:

“Nothing’s ever easy, and there seldom are simple solutions to complex problems.

You need to understand the basics of the problem and work from there.

The company I’m with now, we’re pioneers in neuroblocking. We’re plowing new ground and we found the boulder. We’ll meet with the FDA and get the project moving again. If we hadn’t taken the time to understand the basic principles, we couldn’t keep going.

You must understand what problem you’re trying to solve.

It becomes infinitely more important when you run into the roadblock. You hear about entrepreneurs and perseverance all the time. You need to be effective in your perseverance as well. No. 1, think through your processes. No. 2, hire people much smarter than you.

That’s the other lesson, about vision. You can’t just be farsighted. You need to have trifocals: you have to know what to do in the near term, in 52 days, and you have to have interim goals, in 52 weeks, and then you have to know what you’re doing in 52 months.

One of my favorite savings is, Experience is what you get just after you need it.”

Tom Auth, ITI, builder of the world’s largest wireless security equipment company, according to Rao.

“Thanks to Dileep for putting me in the book, although when my wife saw the title she started looking for more zeros in our bank account.

I had early small successes, then I built from there. Many describe entrepreneurs that are single-minded. Mine just kind of happened. I became an entrepreneur more by necessity than vision. I’ve said I never met a deal I didn’t like. Some roll the dice and bet the farm. I always try to structure things to mitigate the down side.

I love going to work. That is my rule No. 1. If you don’t love it, do something else.

Once I get involved with something I don’t like losing. Someone asked me, to what do you attribute your business success? My answer: I didn’t quit when I should have.

I have three pieces of advice: 1, a small percentage of something really good is better than 100 percent of something worthless. 2, business managers who are good are not easy to manage. 3, use the tax code to your advantage, and flow through taxes away from your investors.”