Why Isn't 1 a Prime Number?

Really, WHY isn't 1 a prime number? Well, why isn't 2.5 a prime number? Let me explain some history and math behind the term "prime number" and what it's useful for, to explain this question I get commonly asked. This video also contains a squirrel cameo and a Dandelion catmeo... Also make sure you've checked out my latest main channel episode about counting in Base 2i here:    • How to Count in Base 2i   Special thanks to my Patreon supporters: Tybie Fitzhugh, Henry Spencer, Mitch Harding, YbabFlow, Plenty W, Quinn Moyer, Julius 420, Philip Rogers, Ilmori Fajt, Brandon, August Taub, Ira Sanborn, Matthew Chudleigh, Cornelis Van Der Bent, Craig Butz, Mark S, Thorbjorn M H, Mathias Ermatinger, Edward Clarke, and Christopher Masto, Joshua S, Max, Joost Doesberg, Adam, Chris Reisenbichler, Stan Seibert, Amy, Izeck, and Max. Patreon:   / comboclass   Main channel:    / comboclass   Reddit:   / comboclass   Discord:   / discord   Combo Class, taught by Domotro, is a crazy educational show where you can have fun learning rare things about math, science, language, and more! This is the channel for Combo Class SHORTS and EXTRAS - make sure you're also subscribed to the main Combo Class channel where full episodes go! DISCLAIMER: any use of fire, tools, or other science experiments in this series is always done in a safe and professional way. Do not try to copy any actions you see in this series yourself.