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.


Check out Bon’s blog at

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