*It’s a special Thursday edition of Math for Grownups, and today we have a guest post from Bon Crowder of Math Four, a great blog that was featured in the Wall Street Journal last month. Here’s her creative take on math and zombies.*

Math isn’t only in real life, it’s in our fantasy and fear worlds too!

I’m a huge fan of *The Walking Dead* – the popular zombie show on AMC that returns October 14.

While watching season two, I started pondering if our heroes even had a chance against the hoards of zombies.

I realized that regardless of how science explains the *start* of a zombie epidemic, the way it continues and the way to stop it is explained with math.

**Zombies make other zombies.**

If you’re bitten or otherwise infected by a zombie, you’ll turn into a zombie yourself. Since zombies never sleep, and are constantly on the lookout for human victims, they have the ability to create many more zombies very quickly.

**Killing zombies is a chore.**

According to *The Walking Dead* the only way to kill a zombie is by ceasing brain function. In other words: removing or impaling the brain.

That sounds simple enough. But just watch one episode and you’ll see how challenging it can be!

**Do we have a chance against a zombie epidemic?**

There are around 30 humans in *The Walking Dead*. Let’s assume that represents reality: there are only 30 humans on the *entire planet*, and the rest of them have been turned to zombies (or will be soon).

We can do a little math to figure out how long it would take for our 30 heroes to rid the world of this epidemic.

There are a little over 7 billion people in the world. That’s 7,000,000,000. (A whole bunch of zeros, I know.)

Each hero will be responsible for killing about 230 million zombies. That’s 7,000,000,000 zombies ÷ 30 heroes.

(Notice I’m rounding like crazy – a fun thing to do when estimating anything. Including zombie deaths.)

Suppose now that each of our heroes could be expected to live 60 more years.

60 years • 365 days = about 22,000 days of life left.

We can calculate how many zombies each hero must kill per day:

230,000,000 zombies ÷ 22,000 days = over 10,000 zombies each day!

Um… we only have 24 hours in a day. That’s 1,440 minutes or 86,400 seconds. So each hero has to kill one zombie every 8 seconds.

Yipes!

*Check out Bon’s blog at MathFour.com. *