[gutnor]

That's the point of the question, isn't it. Finding an opening with the potential buyer before even working on the product. If the buyer does not care about the pen, you will try selling him how cheap, light and not leaking the pen is, so he can buy a box of ten, leave one in each of his jacket and always have a pen ready when he needs it.

In this exercise, you know nothing about the pen, so obviously it is not about the pen - you will not sell the pen if you focus on the characteristic of the pen, you need to find a need for a pen within the interviewer which is the 101 of a sales position. Like those programming questions - of course there are better way to find prime numbers or whatever you need to code - you are not here to discuss the math stuff, you are here to show you can write a few lines of code with a structure, solve a problem, ask the right question, ...