This paper describes patterns of number use in spoken and written English and the main factors that contribute to these patterns. We analysed more than 1.7 million occurrences of numbers between 0 and a billion in the British National Corpus, including conversational speech, presentational speech (e.g., lectures, interviews), imaginative writing (e.g., fiction), and informative writing (e.g., academic books). We find that four main factors affect number frequency: (1) Magnitude – smaller numbers are more frequent than larger numbers; (2) Roundness – round numbers are more frequent than unround numbers of a comparable magnitude, and some round numbers are more frequent than others; (3) Cultural salience – culturally salient numbers (e.g., recent years) are more frequent than non-salient numbers; and (4) Register – more informational texts contain more numbers (in writing), types of numbers, decimals, and larger numbers than less informational texts. In writing, we find that the numbers 1–9 are mostly represented by number words (e.g., ‘three’), 10–999,999 are mostly represented by numerals (e.g., ‘14’), and 1 million–1 billion are mostly represented by a mix of numerals and number words (e.g., ‘8 million’). Altogether, this study builds a detailed profile of number use in spoken and written English.