Infinity and Nothingness

While working with the nine-year-old on division and fractions earlier today, I was reminded of a wrong answer I once gave in a high school math class -- that an integer divided by zero, say, 5/0, equals infinity.

I have no idea where I got the idea (I believe my father told me the same thing when I was learning division) A bit of googling turned up a 12th century Indian mathematician, Bhaskara, and this bit of perhaps inaccurately attributed wisdom:

Bhaskara said that number divided by zero is infinity. (God).

Which reminds me that sitting on my shelf, neglected, is Edna E. Kramer's The Nature and Growth of Modern Mathematics, which tells us that Bhaskara also asked what number multiplied by itself -- squared -- would equal negative one. To this question, he could only suggest the empty set as an answer.

After the nine year old went to bed, I spent the better part of the part of my evening learning card tricks...