Billionaire tech CEO Jack Dorsey reveals the most important question he asks job candidates

Twitter and Square CEO Jack Dorsey says that running a successful business is "all about the people."

He told a group of small business entrepreneurs at the 20th graduation of the Goldman Sachs "10,000 Small Businesses" program that being able to attract the right people means having a deep understanding of company's purpose.

It also means that you can clearly articulate that purpose, and that you can identify alignments and misalignments within the company.

"The most important question I ask whenever I'm interviewing someone is: Why are you here?" Dorsey said.

"If I see passion for our purpose, I know that any skill can be taught."

He added that if people have passion about their work, they will go above and beyond to be successful and fulfill that purpose. If they don't, he said, it will be a drag on the entire organization.

He also highlighted the importance of focusing not just on individual employees, but on how various people complement each other.

If there is misalignment, he said, and if it is because of a purpose, then they make a "hard decision" and part ways.

"It's the hardest thing, but it unlocks potential, it unlocks growth," he said.