You might be surprised to learn you have an emotional response to numbers. What might surprise you even more is learning that reaction is rooted in ancient attempts to understand and predict the universe.

In a nutshell, numerology is the study of the characteristics of numbers. Numerologists believe everything in the world (and the universe, for that matter) can be reduced to or symbolized by a number. As each number has distinct meanings and qualities assigned to it, so do all objects and people associated with that number.

Many people lump numerology into the category of what they consider occult practices, right alongside astrology and phrenology. Whether it’s legitimate or junk is immaterial. The simple fact is that numerological concepts are woven throughout our lives, including the way we work. By becoming familiar with those concepts, we can use them to our advantage.

If you’re unfamiliar with numerology or think it’s a New Age invention, you should know the study of numbers — and the characteristics they allegedly represent — is as old as history itself. Most of today’s numerological concepts are rooted in ancient Hebrew beliefs formed thousands of years before the birth of Christ. Look closely through literature and theology from ancient times to the present day, and you’ll see their influence.

Skeptical? Reach for your Bible. Think it’s just a coincidence that it rained on Noah and his menagerie for 40 days and 40 nights … and Jesus also wandered into the desert to face temptation for 40 days and 40 nights? Moses lived in Egypt for 40 years, spent the next 40 in the desert, and hung out on Mount Sinai twice for — you guessed it — 40 days and the same number of nights. In fact, there are nearly 150 times the number 40 shows up in significant roles in the Bible.

You’ll find many consistent references to specific numbers throughout the Bible. Numerologists will tell you there’s a reason Jesus suffered exactly five wounds on the cross, as well as why He had 12 apostles instead of 11 or 13. The Book of Revelation is a numerologist’s dream, packed full of references to specific numbers. As a person of faith, you may not put much stock in the power of numbers in Biblical books, but those numbers were meaningful to the people who wrote them.

Numerology’s significance appears in our daily lives, too. Have you ever noticed how many sets of things use the same numbers? Seven days of the week, seven daily sins, seven continents, seven colors in the rainbow–the list goes on and on. When people assemble lists, they also tend to be built upon certain numbers. “Three ways to save on groceries.” “Five strategies for safer spelunking.” “The ten best ways to lower your taxes.” When was the last time you saw a blog post headlined “11 popular vacation spots”? You probably haven’t, because “eleven” just doesn’t sound right to most people. And even non-superstitious folks typically have an aversion to 13.

To numerologists, certain numbers are viewed as more complete than others. They’ll tell you that’s why we often see things in sets of three, five, seven, ten, and 12. And because those sets have become the norm in our daily lives, we’re more comfortable with them.

Now, I’m not suggesting you adopt a belief that numbers have mysterious powers. Nor am I implying your personal religious beliefs are secretly driven by numbers. What I am pointing out is the fact people have subconscious reactions to numbers that are rooted deeply in our cultural history. Educating yourself about those reactions can help you make your communications more effective.

For example, if you’re developing a blog post offering lawn care advice, your message is likely to be better received if the headline says, “Five ways to improve your lawn” than if it offers “Four ways to improve your lawn.” I know it may seem silly, but people will have greater interest and confidence in your message if it contains five ideas instead of four.

Similarly, if you offer a “12-point service package,” it will be significantly more attractive to your customers than an “11-point service package” or (gasp!) a “13-point service package.” Don’t believe me? Run some split tests, and you’ll see I’m not making this up.

The most effective marketers have a strong understanding of psychology and the many subconscious factors affecting the decisions people make. Becoming familiar with the basics of numerology may seem to be a little “out there,” but it can provide some interesting insight.

Scott Flood creates effective copy for companies and other organizations. His guide to evaluating freelance creative talent, The Smarter Strategy for Selecting Suppliers, can be downloaded at http://sfwriting.com.