3. Spell out years and months in stating ages: e.g., Edward is five years and four months old.
4. Spell out numbers of centuries, dynasties, military bodies, streets and thoroughfares, sessions of Congress.
5. In statistical or technical matter figures should be used: e.g., The paper to be used is 33 × 44 inches, and weighs 120 pounds to the ream.
6. Spell out, in ordinary reading matter, all numbers of less than three digits: e.g., We have twenty-five titles, amounting to 250,000 volumes in all.
7. If, in a group of numbers, some consist of three digits and others of less, use figures for all: e.g., The packages contain, respectively, 50, 85, and 128 sheets, not fifty, eighty-five, and 128.
8. Spell out round numbers, but use figures for specific, even though approximate statements: e.g., The population of the United States is about one hundred millions; but, The population of the United States is 92,000,000.
9. Always spell out a figure, whatever its size, when it begins a sentence. If for any reason this is impracticable the sentence must be reconstructed.
10. In ordinary reading matter spell out the time of day, but in enumerations, and {33} always in connection with A.M. and P.M., use figures, omitting the word o’clock: e.g., The doors open at 7:30 P.M.
DIPHTHONGS
1. Avoid all diphthongs, especially æ and œ, but retain æ and œ in Latin words and in nominal English forms like formulæ and other plurals, arbor vitæ, etc. Established English words having now or formerly the ligature æ or œ are generally written with the simple e.