When I was in high school, I read a book called Infinity: Beyond the Beyond the Beyond. I don’t remember much about it, but I’ll never forget the title. The concept of infinity in its … well, infiniteness… can keep my mind occupied for a long time. And the idea of going “beyond the beyond” — and then beyond that! — provided more delicious food for thought. I sometimes think about that title and the mind-candy of endlessness when I’m speaking at a school, as I was last week in West Chester, PA, and someone asked, “What’s the biggest number?” It’s a question I often hear. The conversation usually goes something like this:
Child: What’s the biggest number in the whole wide world?
David: Do you think there is such a thing as the biggest number?
Audience: half “Yes,” half “No”
David: Will someone please tell me what you think the biggest number is.
Children, variously: billion, trillion, quadrillion, quintillion, googol, googolplex, etc.
David: Hang on. Let’s suppose you think “quintillion” is the biggest number. Then what about “quintillion-and-one”? Isn’t that bigger? And if that’s the biggest, what about “quintillion-and-two” — even bigger, right?
This usually leads to a triumphant retort about an enormous number familiar to many children (much less familiar to their parents and teachers):
Child: Googol has to be the biggest!
David: What’s a googol?
Many children know that “googol” is the name for a very large number — a one followed by a hundred zeros. This is an exciting concept. In my book G is for Googol: A Math Alphabet Book, I tell the story of how “googol” got its name from a nine-year old boy. Surely it is tempting to call googol “the biggest number,” but that’s a non-starter.
Me: If you think googol is the biggest number, then what about googol-and-one? Or two googol? Or a googol googol?
Almost inevitably, at this point someone proffers an even bigger number, “googolplex.” It is true that the word “googolplex” was coined Continue reading


ou get your ideas?” This is a question I often hear from children, along with “How old are you?” and “How much money do you make?” I like to tell them that ideas are everywhere. “You just have to keep your eyes open, your ears open and your mind open.”
I know how to get kids really excited about math. Show them popcorn. Lots of popcorn. It’s one of my math props when I speak at schools. I pull out bags of popcorn that grow by powers of ten from one to ten to one hundred to one thousand and so on. Are you wondering how big the bags get? That’s exactly what the kids are wondering, and they’re at the edge of their figurative seats waiting to find out (I say “figurative” because they’re usually sitting on the floor). Their growing excitement is abated only momentarily when I tell them they won’t get to eat my popcorn (and wouldn’t want to eat it because I popped it in 1985). They groan but immediately go back to screaming with delight as a bag of popcorn ten times larger than the last one appears before their eyes. 








