Basic Math and Pre-Algebra For Dummies (2 page)

Once upon a time, you loved numbers. This isn't the first line of a fairy tale. Once upon a time, you really did love numbers. Remember?

Maybe you were 3 years old and your grandparents were visiting. You sat next to them on the couch and recited the numbers from 1 to 10. Grandma and Grandpa were proud of you and — be honest — you were proud of yourself, too. Or maybe you were 5 and discovering how to write numbers, trying hard not to print your 6 and 7 backward.

Learning was fun.
Numbers
were fun. So what happened? Maybe the trouble started with long division. Or sorting out how to change fractions to decimals. Could it have been figuring out how to add 8 percent sales tax to the cost of a purchase? Reading a graph? Converting miles to kilometers? Trying to find that most dreaded value of
x?
Wherever it started, you began to suspect that math didn't like you — and you didn't like math very much, either.

Why do people often enter preschool excited about learning how to count and leave high school as young adults convinced that they can't do math? The answer to this question would probably take 20 books this size, but solving the problem can begin right here.

I humbly ask you to put aside any doubts. Remember, just for a moment, an innocent time — a time before math-inspired panic attacks or, at best, induced irresistible drowsiness. In this book, I take you from an un-derstanding of the basics to the place where you're ready to enter any algebra class and succeed.

Somewhere along the road from counting to algebra, most people experience the Great Math Breakdown. This feels something like when your car begins smoking and sputtering on a 110°F highway somewhere between Noplace and Not Much Else.

Please consider this book your personal roadside helper, and think of me as your friendly math mechanic (only much cheaper!). Stranded on the interstate, you may feel frustrated by circumstances and betrayed by your vehicle, but for the guy holding the toolbox, it's all in a day's work. The tools for fixing the problem are in this book.

Not only does this book help you with the basics of math, but it also helps you get past any aversion you may feel toward math in general. I've broken down the concepts into easy-to-understand sections. And because
Basic Math & Pre-Algebra For Dummies
is a reference book, you don't have to read the chapters or sections in order — you can look over only what you need. So feel free to jump around. Whenever I cover a topic that requires information from earlier in the book, I refer you to that section or chapter, in case you want to refresh yourself on the basics.

Here are two pieces of advice I give all the time — remember them as you work your way through the concepts in this book:

• Take frequent breaks.
  Every 20 to 30 minutes, stand up and push in your chair. Then feed the cat, do the dishes, take a walk, juggle tennis balls, try on last year's Halloween costume — do
  something
  to distract yourself for a few minutes. You'll come back to your books more ­productive than if you just sat there hour after hour with your eyes ­glazing over.
  
• After you've read through an example and think you understand it, copy the problem, close the book, and try to work it through.
  If you get stuck, steal a quick look — but later, try that same example again to see whether you can get through it without opening the book. (Remember that, on any tests you're preparing for, peeking is probably not allowed!)
  

Although every author secretly (or not-so-secretly) believes that each word he pens is pure gold, you don't have to read every word in this book unless you really want to. Feel free to skip over sidebars (those shaded gray boxes) where I go off on a tangent — unless you find tangents interesting, of course. Paragraphs labeled with the Technical Stuff icon are also nonessential.

If you're planning to read this book, you likely fall into one of these categories:

• A student who wants a solid understanding of the basics of math for a class or test you're taking
  
• An adult who wants to improve skills in arithmetic, fractions, decimals, percentages, weights and measures, geometry, algebra, and so on for when you have to use math in the real world
  
• Someone who wants a refresher so you can help another person understand math
  

My only assumption about your skill level is that you can add, subtract, multiply, and divide. So to find out whether you're ready for this book, take this simple test:

•   5 + 6 =___
  
• 10 − 7 =___
  
•   3 × 5 =___
  
• 20 ÷ 4 =___
  

If you can answer these four questions, you're ready to begin.

Throughout the book, I use four icons to highlight what's hot and what's not:

This icon points out key ideas that you need to know. Make sure you understand before reading on! Remember this info even after you close the book.

Tips are helpful hints that show you the quick and easy way to get things done. Try them out, especially if you're taking a math course.

Warnings flag common errors that you want to avoid. Get clear about where these little traps are hiding so you don't fall in.

This icon points out interesting trivia that you can read or skip over as you like.

In addition to the material in the print or e-book you're reading right now, remember that (as they say on those late-night infomercials) “There's much, much more!” Be sure to check out the free Cheat Sheet at
www.Dummies.com/cheatsheet/basicmathanndprealgebra
for a set of quick reference notes on converting between English and metric measurement units; using the order of operations (also called order of precedence); working with the commutative, associative, and distributive properties; converting among fractions, decimals, and percents; and lots, lots more.

In addition,
www.Dummies.com/webextras/basicmathandprealgebra
also contains a set of related material on topics like how to use factor trees to find the greatest common factor (GCF) of two or more numbers; how to use the percent circle, a helpful tool for solving percent problems; how to calculate the probability of getting certain rolls in the casino game of craps, and more.

And remember that in math, practice makes perfect. The
Basic Math & Pre-Algebra Workbook For Dummies
includes hundreds of practice problems, each group with a brief explanation to help you get started. And if that's not enough practice,
1,001 Practice Problems in Basic Math & Pre-Algebra For Dummies
provides lots more. Check them out!

You can use this book in a few ways. If you're reading this book without immediate time pressure from a test or homework assignment, you can certainly start at the beginning and keep going to the end. The advantage to this method is that you realize how much math you
do
know — the first few chapters go very quickly. You gain a lot of confidence, as well as some practical knowledge that can help you later, because the early chapters also set you up to understand what follows.

If your time is limited — especially if you're taking a math course and you're looking for help with your homework or an upcoming test — skip directly to the topic you're studying. Wherever you open the book, you can find a clear explanation of the topic at hand, as well as a variety of hints and tricks. Read through the examples and try to do them yourself, or use them as templates to help you with assigned problems. Here's a short list of topics that tend to back students up:

• Negative numbers (Chapter
  4
  )
  
• Order of operations (Chapter
  5
  )
  
• Word problems (Chapters
  6
  ,
  13
  ,
  18
  , and
  23
  )
  
• Factoring of numbers (Chapter
  8
  )
  
• Fractions (Chapters
  9
  and
  10
  )
  

Generally, any time you spend building these five skills is like money in the bank as you proceed in math, so you may want to visit these sections several times