APPENDIX A
Working with Numbers:
Binary and Hexadecimal
You learned the fundamentals of arithmetic so long ago, it is hard to imagine
what it would be like without that knowledge. When you look at the number
145, you instantly see “one hundred forty-five” without much reflection.
You generally see numbers in what is called the decimal format. There are,
however, other formats that can be used for numbering. When working with
computers, the two systems that come up the most are binary and hexadecimal.
Understanding binary and hexadecimal requires that you reexamine the number
145 and see it not as a number, but as a code for a number.
Start small: Examine the relationship between the number three and “3.” The
numeral “3” is a squiggle on a piece of paper; the number three is an idea. The
numeral is used to represent the number.
The distinction can be made clear by realizing that three, 3, |||, III, and *** all
can be used to represent the same idea of three.29 0672327112_app_a.qxd 11/19/04 12:30 PM Page 807