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Author Insight
The Vast Math Domain
One of the reasons I wrote this book is because I wanted to make mathematics more interesting for students. For many younger students, math just seems like repetitive arithmetic operations. Let's face it, there's not a lot of excitement there - though it might be necessary. The domain of mathematics is absolutely huge, though, and it's our job as teachers to at least show students more of the domain.
Book Excerpt
Beyond Infinity
Nine has a curious property that makes it very useful in a lot of those “magic” number tricks where you choose a number and after a few steps someone tells you the amazing result. For example, pick a number besides zero. Multiply it by nine. Add the digits together, and keep adding the results together until you reach a single digit. Result: nine. Try it again if you don’t believe me. Just make sure to keep adding the digits together until there’s just a single digit left. For example 9 × 9 = 81, and then 8 + 1 = 9. Or 23 × 9 equals 207, and 2 + 0 + 7 = 9. Here’s another: 177 × 9 = 1593, and 1 + 5 + 9 + 3 = 18 and then 1 + 8 = 9 as a single digit.
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