You may not realise it but your favourite number isn't four, or seven, or 42. It's three. Three is everyone else's favourite number too, and you can use this simple truth to add punch to anything you write, from an email to a book.

There's something magical about three. Pythagoras, who knew a thing or two about three-sided shapes, called three 'the perfect number'. In Latin there was a saying – omne trium perfectum – which translates as 'everything that comes in threes is perfect'. And as any artist or photographer will tell you, dividing a frame into thirds is the 'go to' way to achieve a visually appealing composition.

In popular culture, threes appear commonly in nursery rhymes (Three Little Pigs, Goldilocks and the Three Bears), in memorable film titles (Planes, Trains and Automobiles, Sex, Lies and Videotape) and in comedy ("An Englishman, an Irishman and an American walk into a bar..."). The trilogy has been a popular format for extended storytelling for decades (Lord of the Rings, The Hunger Games).

No one seems to be able to pin down exactly why three is such a comfortable number. One argument is that a group of three is more interesting than a simple pair while it adds nothing extraneous (as four does).

A group of three is simplicity and complexity rolled into one.

Writing in threes

There are three (of course) ways you can use the concept of threes to improve your writing.

• Phrase in threes: look back through this article and you'll see numerous examples of how three words or phrases can be grouped in a sentence, or three sentences can be grouped in a paragraph. A good approach is to use the third word, phrase or sentence to add a twist to what you want to say (as I did in the opening sentence – if you didn't get the joke, read this).
• Subdivide into threes: when you have more material to cover than can be grouped under three headings, try to identify three major topics. Then, ideally, use groups of three subheadings under those. Along the same lines, when using bullet points try to present those in groups of three too.
• Structure in threes by using the classic 'beginning, middle and end' approach to outlining anything from an argument to a story. Put another way: tell them what you're going to tell them, tell them, then tell them what you told them. When looking to write a book but confronted by having too much to tell, consider breaking your information into three. I often counsel my ghostwriting clients that three books are much better than one if you're trying to build your reputation as an expert.

A rule made to be broken

No one seems to have told J K Rowling that three is the magic number. Clearly both she and her publishers, not to mention her fans, were happy for her to keep churning out Harry Potter books until she'd reached the next magic number: seven.

The 'rule' or guideline of threes is, like any rule, made to be broken. However, like any rule, it is best to be well practiced at using it before you make a choice to break it. My suggestion is that you give it a try and see how it feels. After a while you'll find it feels unnatural not to add that third item to a list.

Oh, and if you'd like to learn more about the power of three, there's a website dedicated to it. Visit The Book of Threes for more than a few examples and discussions on the topic.