What: round-up wisely all the numbers written in your documents, slides or charts.

Why: including long numbers in your documents or slides is a very bad idea. It is adding clutter to your document, deviating attention and more important, it is damaging your credibility.

How: aligning the numbers’ precision with the confidence level of your estimations, the audience expectations and common sense. As a rule of thumb (for most use cases) avoid using more than one decimal point.

Where: in any written document, including axis labels and chart annotations.

Examples:

a) Average ticket price predicted is $58.3241

This means that you are cheap ($0.0001 is relevant for you) and even worse, that you are so confident on your analysis (after all those hypotheses and assumptions…) that you trust your results so much as the Pi number.

b) Next year we will lose 33.1 customers per month

I know, you do not want to lose precision, and in some cases it is ok to keep the decimal point when counting people or towels, but… are you really so sure about your estimations? Is your audience expecting that level of precision? By the way, note that 33 is much more memorable than 33.1.