# Technical Writing Best Practices – By the Numbers

#### Technical Writing Best Practices – By the Numbers If a word is misspelled or misused in a text, it distracts the reader from your content. The same is true for the way you use numbers in your documents.

Are there 6 spark plugs in a set or six spark plugs in a set? Can a reader interpret “hundred-thousand” as a range (100 to 1,000) or a single number (100,000)?

There are general rules guided by best practices in the industry. The following are general style guide suggestions for staying consistent – and avoiding ambiguity – in the way you represent numbers in a technical document:

• Numbers < 10 are typically written as words, for quantities that have been counted (The company has six networks.)
• Numbers > 9 are written in numerals (e.g, 18 months or \$2.1 billion)
• If a number is the result of a calculation or measurement, it must be written in numerals (The stock showed a 0.4 percent loss since last week.)
• Ensure the article matches the number (an 18 percent increase, a 10 percent decrease)
• Do not begin your sentence with a numerical number (85 orders were placed. Eighty-five orders were placed.)
• Hyphenate numbers 21 through 99 when they are written as words (Ninety-five out of 100 attempts resulted in success.)
• When writing a range of numbers, use an em dash, versus an en dash (1962–1980 or \$400—\$600, not 1962-1980 or \$400-\$600)
• Use correct descriptors
• Quantities measured = less than, more than, amount of: “Less than five percent…”
• Quantities counted = fewer, greater than, number of: “Fewer than half…”
• Dimensions = smaller than, larger than
• Ratios are expressed in numerals (The ratio of blue pigment to red pigment is 4 to 1. Do not write 4:1.)
• Mathematical operations and dimensions are written as numerals (a factor of 6, 8.5×11 sheet of paper)
• When telling time, use numerals instead of words (The shift starts at 7:00.)