Number and Unit Formatting Guide

This reference defines conventions for numbers, units, and statistical reporting in academic papers.

SI Unit Formatting

• Always insert a space between the number and the unit: 5 kg, 100 mL, 25 °C
• Exceptions: percentage (5%), degree symbol alone (45°), currency ($100)
• Use SI base/derived units; spell out non-standard units on first use
• In LaTeX: use \SI{5}{kg} (siunitx) or 5\,kg for thin space
• In Typst: use 5 #unit("kg") or manual thin space 5#h(0.15em)kg

Number-Word Thresholds

Context	Rule
Sentence start	Always spell out: "Twenty participants..."
Values 1-9 in prose	Spell out: "three experiments", "five categories"
Values 10+ in prose	Use digits: "12 features", "256 samples"
Precise measurements	Always digits: "3 mL", "7 days"
Large round numbers	Mixed: "1.2 million", "3 billion"
Adjacent numbers	Alternate forms: "two 3-layer networks"

Statistical Reporting

Measure	Format	Example
Percentage	1 decimal place	85.3%
Mean +/- SD	2 decimal places	3.14 +/- 0.05
p-value	Exact (3 sig figs) or threshold	p = 0.003, p < 0.001
Correlation	2-3 decimal places	r = 0.87
Confidence interval	Same precision as estimate	[2.10, 4.18]
Effect size (Cohen's d)	2 decimal places	d = 0.75
F-statistic	2 decimal places with df	F(2, 47) = 3.85
t-statistic	2 decimal places with df	t(49) = 2.10
Chi-square	2 decimal places with df	chi-sq(3) = 7.81

Consistency Rules

• Precision must be consistent within each column of a table
• Precision must be consistent for the same measure across the paper
• Report exact p-values when p >= 0.001; use "p < 0.001" otherwise
• Never report "p = 0.000" — use "p < 0.001"

Range Formatting

• Use en dash for number ranges: "10--20", "pp. 1--15"
• In LaTeX: 10--20 renders as 10–20
• In Typst: 10--20 or 10#sym.dash.en 20
• Do not use "from X-Y"; use "from X to Y" or "X--Y"

Large Number Formatting

• Use comma separators for numbers >= 1,000: 1,024, 10,000
• In some European venues, use period: 1.024, 10.000 — check venue guide
• Scientific notation for very large/small: 3.2 x 10^5, 1.5 x 10^{-3}