NUMERAL Letters are those letters of the alphabet which are generally 7 used for figures, as 1, one; V, five; X, ten; L, fifty; C, a hundred; D, five hundred; M, a thousand; and so on. It is not agreed how the Roman numerals originally received their value. It has been supposed, as we have observed in the article Number, that the Romans used Μ to denote 1000, because it is the first letter of mille, which is the Latin word for 1000; and C to denote 100, because it is the first letter of centum, which in Latin means 100. It has also been supposed that D, being formed by dividing the old Μ in the middle, was therefore appointed to stand for 500, that is, half as much as the Μ stood for when it was whole; and that L being half a C, originally written E, was for the same reason used to denominate fifty. But what reason is there to suppose that 1000 and 100 were the numbers which letters were first used to express? And what reason can be assigned why D, the first letter in the Latin word decern, ten, should not rather have been chosen to stand for that number than for 500, because it had a rude resemblance to half an Μ? But if these questions could be satisfactorily answered, there are other numeral letters which have never yet been accounted for at all. These considerations render it probable that the Romans did not, in their original intention, employ letters to express numbers at all. The most natural account of the matter seems to be this: The Romans probably put down a single stroke, I, for one, as is still the practice of those who score upon a slate or with chalk. This stroke, I, they doubled, trebled, and quadrupled, to express 2, 3, and 4; thus, II., HL, IIII. So far they could easily number the strokes with a glance of the eye. But they presently found that if more were added it would soon be necessary to tell the strokes one by one. For this reason, then, when they came to 5, they expressed it by joining two strokes together in an acute angle, thus, V; which will appear the more probable, if it be considered that the progression of the Roman numbers is from 5 to 5, that is, from the fingers on one hand to the fingers on the other. Ovid has touched upon the original of this in his F'asti (lib. iii.), and Vitruvius has made a similar remark.

After they had made this acute angle V for five, they added the single strokes to it to the number of four, thus VI., VII., VIII., V1HL, and then, as the strokes could not be further multiplied without confusion, they doubled their acute angle by prolonging the two lines beyond their intersection, thus, X, to denote two fives, or ten. After this they doubled, trebled, and quadrupled this double acute angle thus, XX., XXX., XXXX.; they then, for the same reason which induced them first to make a single and then to double it, joined two single strokes in another form, and instead of an acute angle, made a right angle, L, to denote fifty. When this fif ty was doubled, they then doubled the right angle thus, E, to denote 100; and having numbered this double right angle four times, thus, EC, LEE, EE EE, when they came to the fifth number, as before, they reverted it, and put a single stroke before it thus I□, to denote 500; and when this 500 was doubled, then they also doubled their double right angle, setting two double right angles opposite to each other, with a single stroke between them, thus, El J, to denote 1000. When this note for 1000 had been four times repeated, then they put down I□□ for 5000, EEI∑1□ for 10,000, and IJ□□ for 50,000, and EEEU□□ for 100,000, IJJJJ for 500,000, and ECEEI□□J□ for one million.

That the Romans did not originally write Μ for 1000, and C for 100, but square characters, as they are represented above, we are expressly informed by Paulus Manutius; but the corners of the angles being cut off by the transcribers for despatch, these figures were gradually brought into what are now numeral letters. When the corners of EI□ were made round, it stood thus CIO, which is so near the Gothic en, that it soon deviated into that letter; so 13 having the corners rounded, stood thus, 10, and then easily deviated into D. L also became a plain C by the same means; the single rectangle which denoted fifty was, without alteration, a capital L; the double acute angle was an X; the single acute angle a V consonant; and a plain single stroke the letter I; and thus these seven letters, M, D, C, L, X, V, 1, became numerals.

Numeral Characters of the Arabs are those figures which are now used in all the operations of arithmetic in every nation in Europe. See the article Arithmetic.