Ever wondered what the numbers on your toaster... really... mean? This video explains.

It certainly isn't minutes, as the head-to-head toast race in the video explains. In fact, it turns out that they don't really mean anything of real merit. Different toasters use different methods to time time their heating—be it a bi-metallic strip that changes shape to measure temperature increase or a capacitor that's charged and makes your slices pop up when a given voltage is reached. But what they virtually all share in common is that they're pretty much arbitrary—so you'll still have to experiment to see if you prefer a 3 or a 4 level of cooked-ness. Sorry. [Tom Scott]