## Kill the Mathematical Hydra

How do you defeat a creature that grows two heads for every one head you chop off? You do the math. Mathematician Kelsey Houston-Edwards explains how to defeat a seemingly undefeatable monster using a rather unexpected mathematical proof. In this episode you’ll see mathematician vs monster, thought vs ferocity, cardinal vs ordinal. You won’t want to miss it.

## How to Divide by “Zero”

We all know you can’t divide by the number zero. But in some sense the notion of “dividing by zero” appears every time you use modular arithmetic! The structures that underlie this “modding business” are called equivalence relations and quotient sets
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