Lisa Roye, age 15, of Louisville, Kentucky, for her question:

What in the world is a googol?

It sounds like the sort of invention you would expect from a smart younger brother. And this is just about the size of it. Edward Kasner was teaching a few math tricks to his nine year old nephew. Naturally, this led to a barrage of questions, such as what is the biggest number in the world? Since there seemed to be no satisfactory answer, the young student invented a stupendous number of his own and named his invention the googol. He accomplished this feat by making use of a math gimmick called the power of ten.

The trick is to multiply a number by a string of 10s and the cunning device is written in figures of two sizes. It may be a normal sized 10 with a small 3 up where its right ear should be. In this case, the 10 is multiplied three times and the answer is 1,000. A googol is 10 to the power of 100, or one plus a string of 100 zeros. This enormous number is beyond the imagination    but the googolplex is a googol times larger.