More things I didn’t know: there are six AAA batteries inside a 9 volt battery. Actually, they’re AAAA batteries which are smaller diameter, but they’ll apparently work in many devices that uses AAA batteries. UPDATE: One person at the link below reported that it damaged his electronics, so reserve this for McGyver-style emergencies. And who doesn’t have those?
Hard to believe, but here’s a video demonstration. This is definitely going on this year’s list of 2,007 things I learned in 2007.

Well I have learned something new today.
they didn’t used to… they used to have 6-7 “prismatic” cells in a stack. When I was a kid I ripped quite a few apart when they died…
Back when I was selling batteries for my soul.. er.. a pittance, AAAA batteries were a new thing, made available for a slew of new pen-sized devices, mostly lasers and little pen-clocks. I bet they just shifted production over when it became cheaper to cram the cases full of these instead of the prismatics.
actually their called AAAA’s or quadrouple A’s and i think that you can actually use them as triple A’s sometimes but i havn’t tried to use them as AAA’s
NOT TRUE, I TORE ONE OPEN NOT TO FIND ANY KIND OF BATTERIES.