Want to work at Google? This will help you pass interview.

How many ping pong balls can fit into an airplane? For example Boeing 747 or 737?

This video shows how to answer guesstimate problem that supposedly appeared on Google or Goldman Sachs job interviews.
But unlike in many other places, the point is not to give you exact sizing of ping pongs and technical specifications of airplanes, because you don't have this information with you during the job interview.
Instead this video shows how to rely on only what you have in your head and whatever is available during the interview to get a reliable answer.

This type of questions is designed to get the exact answer, but to test your skills in problem solving, imagination and attention to the details.
And this question "How many ping pong balls can fit into Boeing" though it's easy to state, brings many variables, room for establishing details and for showing your math skills.

In this first part I explain how to estimate number of ping pong balls that can fit into one cubic meter and how to get diameter of one ball. We will need no math formulas got reasonable answer.

This is the most important parameter in the whole guesstimation, because it is raised to the power of 3 in the calculation, so if you miss it by as little as 10% it will skew the end result by 33%.

I also offer some points in how to negotiate best conditions regarding details not stated in the problem and how to go through the whole process having in mind that the point is not the answer, but showing your thinking process.

In the second part that will be linked here we will consider how much space we have in the airplane and where actually do we want to stuff the ping pongs. We will get our final answer and then verify it.