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Book Review: Making Numbers Count: The Art and Science of Communicating Numbers

Numbers are essential – we use them every day to make sense of the world – but humans aren’t built to understand them. … While the numbers in our world have gotten increasingly complex, our brains are wired in the past. How can we translate millions and billions and milliseconds and nanometers into ideas we can comprehend and use?

Making Numbers Count: The Art and Science of Communicating Numbers, (2022), by Chip Heath and Karla Starr is a slim volume that addresses an important topic, communicating numbers in ways that the average person can understand and remember. We measure, analyze, and report on everything from demographics, economics, finance, and sociology to research in the physical sciences. In a world that is more and more quantitative every day, we are entranced with numbers, but give little thought as to how we communicate them.

The authors draw on their experience in crafting the book. Chip Heath is a professor at the Stanford Graduate School of Business and is co-author of the popular books Made to Stick, Switch, Decisive, and The Power of Moments. The idea for the book came from one of his student’s questions and is now an established part of his teaching. Karla Starr is a writer and member of the National Association of Science Writers. She is the author of Can You Learn to Be Lucky? Why Some People Seem to Win More Often than Others.

Heath and Starr observe that the human brain is designed to recognize and manipulate very small numbers … often limited to the numbers one through five … where everything else becomes “lots.” Numbers have played a role in human development, starting with counting, then the use of numbers, and finally mathematics. Unfortunately, “while our cultural math infrastructure has changed, our brains are still the same from a biological perspective.”

Our minds go blank trying to understand large numbers, like 94 billion, which is the distance in light-years across the observable universe; small numbers, like 9.1093837015 × 10−31, the approximate weight of an electron in kilograms; fractions like 1/1,836, which is the mass of an electron compared to a proton; or complicated decimals, like 3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679, which represents the first 100 digits of Pi.

Making Numbers Count explains how to make numbers understandable with examples showing how to explain almost anything quantitative. It describes techniques to put numbers in a simple context that will make an impact on the listener and provide a memorable description. The authors provide a general principle in each chapter and then give specific examples, showing how reframing a number can make it understandable and memorable. Here are examples from the first few chapters.

“Avoid Numbers: Perfect Translations Don’t Need Numbering.” This may sound counterintuitive, but Heath and Starr give excellent examples.

Original Statement. 34% of White applicants and 14% of Black applicants without records received callbacks, compared to 17% and 5% with records.

Revised Statement. White job applicants who had served jail time for a felony were more likely to receive a callback than were Black applicants with impeccable records.

The numbers in the original statement are hardly memorable, but the observation that white job applicants with criminal records received more callbacks than black applicants with no record is something you will remember. This brings out both the racism of the situation and its impact on Black applicants.

“Try Focusing on 1 at a Time.” The authors note that “The quickest route to having people understand your number is to start with something simple, a well-understood part of the overall scene.”

Original Statement. There are about 400 million civilian-owned firearms in the United States.

Revised Statement. There are about 330 million citizens in the United States and more than 400 million firearms … or enough for every man, woman, and child to own 1, and still have around 70 million firearms left over.

This example makes it clear that there are many firearms in the United States by tying them to every citizen.

This type of comparison is effective when comparing numbers over a range or span to numbers in a single event. For example, it is one thing to know that the basketball player Lebron James scored over 35,000 points in his career, but another to know that he averaged over 27 points per game for every game he played. Few players score 27 points in a single game, much less averaging that number every game a career.

For the reader or listener to understand context, examples must be tailored with the audience in mind. While it might resonate with someone from Charlottesville to say that something is as large as “Albemarle County,” it makes no sense if the reader or listener is from Europe and has never heard of Albemarle County.

“Favor User-Friendly Numbers.” In cases where precision is not required, it is acceptable to round numbers to a simpler figure. For example, instead of saying 2,842,900, say about 3 million. Is 2,842,900 or 3 million more easily understood and remembered? The authors note that “the information it conveys is functionally the same.” They list three rules for applying this principle: Rule #1. Simpler is better: Round with Enthusiasm, Rule #2. Concrete is Better: Use Whole Numbers to Describe Whole Objects, Not Decimals, Fractions, or Percentages, and Rule #3. Follow the Rules But Defer to Expertise. Rules 1 and 2 May be Trumped by Expert Knowledge.

These three principles give the reader a flavor of what is to come. Other chapter titles include:

  • “Convert Abstract Numbers into Concrete Objects”

  • “Recast Your Number into Different Dimensions: Try Time, Space, Distance, Money, and Pringles”

  • “Human Scale: use the Goldilocks Principle to Make Your Numbers Just Right”

  • “Bring Your Number into the Room with a Demonstration”

The authors present around twenty principles, clearly stated and with multiple examples. These help the reader communicate information about numbers better in an easy-to-understand and memorable way.

As a side note, this is one of the few books where you won’t want to miss the endnotes. Rather than dry references, the endnotes are informative and entertaining, describing the source material used throughout the book.

Making Numbers Count is a delightful find. It addresses a subject that should be second nature to anyone who works with numbers … how to make them understandable and memorable.


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