The Writer's Desk Book / Being a Reference Volume upon Questions of Punctuation, Capitalization, Spelling, Division of Words, Indention, Spacing, Italics, Abbreviations, Accents, Numerals, Faulty Diction, Letter Writing, Postal Regulations, Etc.

by William Dana Orcutt

I, signifies one, because it is the smallest letter.

V, five, because it is sometimes used for U, the fifth vowel.

X, ten, because it represents two V’S.

L, fifty, from its resemblance to the lower half of C.

C, a hundred, centum.

I

or D, five hundred, the half of CI

.