Yesterday’s useless trivia question was How far does the average office chair travel in a year? Today’s useless trivia question is “On average, how long a line can be drawn with an average pencil before it runs out of lead/graphite?”

Here is how I tried to answer it.

  1. The average pencil is about 10 centimeters long.
  2. Each time you draw a line of about 1 centimeter with a pencil you use up about 1 micrometer of the pencil.
  3. Therefore when you have used up the pencil you have drawn 1000 * 1 centimeter which is 10 kilometres.

And the actual answer is:

The average pencil contains enough graphite to draw a line that is 35 miles long.

I did better yesterday. But at least I was around the correct order of magnitude. If I had started with a 20 centimeter pencil I would have done better. 🙂

One Response to “How long a line can a pencil draw?”

essny wrote a comment on May 4, 2008

why are you being asked such questions?

did you start a new job?

Care to comment?