At first, the ancients developed names for the numbers. They spoke of having one sheep, two sheep, etc. But you can see how difficult it would be to add or subtract columns of numbers expressed only in words. Thus we learn that arithmetic computation did not begin until man came to use symbols for numbers. The kinds of symbols used for numbers went through various changes starting with the simple vertical mark of ancient Mesopotamia, progressing to the combination of the Egyptians, the familiar numerals of the Romans, and finally to our present figures.
We are indebted to the Arabs for our present method of writing numbers. For this reason, the numerals 0 through 9, the ingredients for any number combinations we wish to write, were called Arabic numbers for a long time. But more recently historians have discovered that the system of writing numbers now used by civilized people throughout the world was originated by the Hindus in India. The Arabs learned the system from the Hindus and are credited with having brought it to Europe soon after the conquest of Spain in the eighth century AD. For this reason, we now property call it the Hindu-Arabic system of numerals.
Reading and writing Roman numerals
An early system of writing numbers is the Roman system. It is generally agreed that it is of little practical value in today’s world of advanced mathematics.
Because you will still see Roman numerals used in recording dates, in books, as numbers of a clock face, and in other places, it is worth taking a little time to learn how to read them.
The Roman number system is based on seven letters, all of which are assigned specific values. They are:
I=1, V=5, X=10, L=50, C=100, D=500, M=1000
Here are a few rules to help you read Roman numerals:
Rule 1: When a letter is repeated, its value is repeated.
eg, I=1, II=2, III=3, XX=20, CCC=300
Rule 2: When a letter follows a letter of greater value, its value is added to the greater value.
eg, VI=6, XV=15, LX=60, DC=600
In these examples, observe that the smaller value I after V means add 1 to the 5 to give 6. In the same way, the V following the X means add 5 to 10 which equals 15. Similarly, LX represents 10 added to 50 to give 60. To write 70, merely add XX after the L to give LXX. In like manner, to write 800, add CC after DC to give DCCC.
Rule 3: When a letter precedes a letter of greater value, its value is subtracted from the greater value.
eg, IV=4, IX=9, XL=40, XC=90, CD=400
In these examples, note that the smaller value I, in front of the V, means subtract 1 from 5 to give 4. In the same way, the X in front of the L reduces the 50 by 10 to give 40. In like manner, X in front of C means 100 less 10 or 90 and CD denotes 500 less 100 or 400.
Generally, the symbols are not repeated more than three times to denote a number. To show the number 40 you would write XL and not XXXX. While occasionally 4 is written as IIII, it is usually written a IV.
Rule 4: A horizontal bar over a letter, or letters, indicates that the value given to the letter or letters is to be increased one thousand times.
eg, MCD=1400 but when there is a horizontal bar over MCD, it equals to 1,400,000.
Here are some additional examples of Roman numerals and their Hindu-Arabic number equivalents:
|VII = 7||XLI = 41|
|XI = 11||LXII = 62|
|XIV = 14||CXIII = 113|
|XVIII = 18||CCX = 210|
|XXII = 22||MCM = 1900|
|XXXVII = 37||XICCC (bar over XI) = 11,300|