Guesstimation 2.0: Solving Today's Problems on the Back of a Napkin

I recently picked up Guesstimation 2.0 after it was recommended to me at a networking lunch at the Cavalry and Guards Club (alongside Street-Fighting Mathematics). This however, happened to be a tenner cheaper, so I started here, and I’m glad I did.

It’s a really interesting and surprisingly easy read, even for someone who doesn’t normally spend their evenings tackling mental arithmetic problems.

The first chapter was definitely my favourite. It lays out a simple, almost playful framework for tackling these estimation problems:

1. Write down the answer first – using the Goldilocks principle of “too small, too big, just right” to get yourself in roughly the right region (ideally within a factor of ten).

2. Break the problem into smaller parts, much like the military approach of breaking big issues into manageable ones.

3. Recombine the pieces, pulling it all together into a workable solution.

I’ve dabbled in a few of the questions (I won’t pretend I’ve done them all), and my favourite so far was: How many people are texting or talking on their mobile phone right now? I would love to hear your answers to this, also feel free to reach out for the method I used to come to a very close (but not correct) answer!

That said, it’s not perfect. The book is probably better suited for those with a scientific mind/understanding, and it’s more of a “dip in and out” book than a cover-to-cover read. I also would have liked a few more practical tips woven into later chapters. Still, it’s a fun, thought-provoking read that I’d recommend to anyone curious about sharpening their estimation skills.