Free Trial

Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.

  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint
Share this Page URL
Help

4. Math > 36. Make Friends with Numbers

Make Friends with Numbers

With a little experience, you can learn to recognize many individual numbers by their special properties. Some of these properties can help you with mental arithmetic and memory.

Just like a face in a crowd, a number such as 1,729 probably doesn’t mean much to you. But 1,000,000 looks like a friendly face. With some effort, more numbers can look like friends. Here’s how to get started making their acquaintance.

In Action

Let’s start with some numbers that you’re probably already friendly with—10 and its powers: 100, 1,000, and so forth. Because we use a decimal number system [Hack #40], powers of 10 end in zeros. Companies are aware of that and try to get phone numbers that are multiples of a power of 10, because those numbers are easy to remember. For instance, the publisher of this book, O’Reilly Media, has a local phone number of (707) 827-7000, which is a multiple of 1,000. Multiplying by a power of 10 is easy; you just have to append zeros:


  

You are currently reading a PREVIEW of this book.

                                                                                                                    

Get instant access to over $1 million worth of books and videos.

  

Start a Free 10-Day Trial


  
  • Safari Books Online
  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint