Maybe your favorite interview question is one of the most common interview questions. Maybe it's one of the most common behavioral interview questions. Or maybe you have a less conventional interview question you like to ask, like those asked by these company founders and CEOs.

What is your favorite interview question? To find out, we asked the Inc. community on LinkedIn to provide their favorites, as well as their reasons why. Below are some of the responses; go here and here to see them all.

1. "What is the hardest thing you've ever done?"

The answer can be personal or professional. What the candidate accomplished isn't as important as how -- and why. What were the hurdles? What were the roadblocks? Did the candidate seek help? Does the candidate credit the people who helped?

The answer also can provide insight into how the candidate defines "hard," and how their perspective align with the challenges your business faces.

2. "When have you experienced stellar customer service, and how did that change how you deal with customers?"

This question is a great way to see how candidates define "stellar customer service" -- not just as they experience it, but also in the service they expect themselves to provide. 

3. "What is your personal definition of success?"

Everyone's definition of success is different. (And should be.)

How you define success informs your work habits, your ethics, your willingness to be part of a team, your willingness to sacrifice. Tell me how you define success and I instantly know a lot about you.

4. "Tell me about a time when you felt a change needed to be made in how something was done. How did you come to this conclusion, and how did you get support for the change?"

Every team -- and every company -- can improve. Doing that requires having people who not only see areas for improvement but can actually make those improvements happen.

Listen closely to what the change was, but listen even more closely to how that change was implemented.

5. "Tell me about a time you had to learn a new skill: What was your process, what did you learn about yourself, and what was the end result?"

This is a great behavioral interview question. The "What did you learn about yourself?" portion can be extremely telling.

6. "Up to this point in your life, what is the achievement you are the most proud of?"

The reader that submitted this question likes to ask it last so the person being interviewed leaves on a positive note.

That's a great reason to ask it, but the answer will also tell you what candidates value -- in terms of goals, and about themselves.

7. "Tell me about a time when you felt like a hero." 

This one made me think. (Even given time to think, I'm not sure what my answer would be.)

The reader likes this question because "there's a thin line between cocky and confident. I like posing this question because the interviewee's response will tell me which 'c' (cocky or confident) they fall under."

That makes sense. Was the candidate quietly proud, or did he or she enjoy the public acclaim? Neither is right or wrong, but the answer can indicate how the individual likes to be recognized and praised.

8. "Are you smart, or do you work hard?"

This question is a favorite of Burger King CEO Daniel Schwartz. Schwartz looks for people who feel their success comes from hard work -- because he expects people to work really hard.

9. "What position would you play on a soccer team?"

I like this one because it can indicate personalities. Generally speaking, people who see themselves as strikers tend to enjoy prominent, public roles. People who see themselves as midfielders like to help others, like to be linchpins, like to lead and follow. People who see themselves as defenders like organization, like to be counted on, and don't mind playing a less prominent role.

Of course those are generalities. How will you know why people see themselves certain ways? 

Easy: Ask.

10.  "How will I know you're struggling?" or "How will I know you need help?"

In behavioral terms, this question could be rephrased as "Tell me about a time you struggled to complete a task or project. What did you do?"

A great candidate was willing to ask for help. Isn't that what you want your employees to do when they're struggling?

11. "What did you do to prepare for this meeting today?"

I'm embarrassed to admit I never thought of this one. How -- and to what extent -- the candidate prepared for the interview can indicate a lot not only about his or her interest in the job, but about how this person operates as a professional.

If a candidate can share only platitudes about his or her preparation for something as important as a job interview, that speaks volumes about how this person will prepare for important tasks, meetings, roles, etc. when he or she actually has the job.

12. "What is it about this position that excites you the most?"

Some people want the job title. Some people want the position, not the actual job.

Always hire people who want the job because they like doing the work involved. You don't need people in positions; as Dharmesh Shah says, "You need doers of things that need to get done."

13. "How are are your basic math skills?"

The reader who likes this question asks it first, and most candidates say "excellent" or "strong" or something positive. 

Then he asks what is 20 percent of 35, and he gets a nervous giggle and a wrong answer. (The right answer is 7.) 

To him, it's not a math test. It's a way to gauge how the candidate responds when they make a mistake. Some handle it well. Others do not.

14.  "How do you feel about mopping floors or scrubbing toilets?"

At this reader's company, everyone pitches in on cleaning. Job titles or ownership means nothing; they are all equal.

Even if the candidate responds positively, the reader looks for facial expressions: A quick frown, a look of distaste -- that says a lot more than words.

I used to do something similar when I gave candidates a plant tour. I would find someone performing a manual task, like stacking boxes, and pitch in while talking to the candidate. 

Some would just stand and watch. Some jumped in immediately to help. Others would hesitate, realize just standing there made them look bad, and then jumped in.

Guess which ones I liked? 

15.  "At the end of an interview, I like to ask, 'After you leave today, what are the top three things you want me to have heard about who you are? What do you want to make sure sticks with me about you?'"

Maybe you won't learn much from asking this question. Maybe the candidate will just make a final pitch for why he or she is perfect for the job.

But maybe you will learn something new. And even if you don't, you'll know you gave candidates every opportunity to share their skills, experience, knowledge, and interest in the job -- which is what every interviewer should offer every candidate.

Now it's your turn: What is your favorite interview question?