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Roman Numerals
by Ron Kurtus (updated 18 January 2022)
Roman numerals consist of a numbering system from the ancient Roman Empire that uses certain letters of the alphabet and their combinations to indicate numbers. The system is based on seven major symbols.
When counting with Roman numerals is done by adding a symbol to the previous combination, except for certain numbers before an major symbol.
Problems with using Roman numerals caused the change to our present Hindu-Arabic symbols. However, Roman numerals are still used in special cases.
Questions you may have include:
- What are the major Roman numeral symbols?
- How do you count with Roman numerals?
- What are major problems in using Roman numerals?
- Where are they still used?
This lesson will answer those questions.
Major roman numeral symbols
Major Roman numeral symbols that make up the other numbers are I, V, X, L, C, D, and M. Their values are:
| Symbol | I | V | X | L | C | D | M |
|---|---|---|---|---|---|---|---|
| Value | 1 | 5 | 10 | 50 | 100 | 500 | 1,000 |
Counting
Designating other numbers is done by adding a symbol to the previous combination. Exceptions are for the number preceding a major symbol, such as for 4, which precedes 5. In those cases, a symbol is placed in front. A list of Roman numerals from 1 to 20 gives you an idea of the sequence:
I, II, III, IV, V, VI, VII, VIII, IX, X,
XI, XII, XIII, XIV, XV, XVI, XVII, XVIII, XIX, XX and so on.
Note that 4 is IV, 9 is IX, 14 is XIV, and 19 is XIX.
Also, 40 is not XXXX, rather it is 10 less than 50 or XL. Likewise, 400 is CD.
Strange combinations
Strange combinations include VX, which is five less than ten. Instead, it just should be V. Another situation is DM, which is 500 less than 1000. Instead, it should just be D. (Is this confusing or what?)
Problems with using Roman numerals
When you add two Roman numerals, you may often have to do some conversions. For example, adding 17 and 19, you get XVII + XIX = XIXVII, which would have to be rearranged and converted into IXXII = XXVI. Certainly, that is awkward.
Multiplying and dividing with Roman numerals is even more difficult. (I don't know how people in those days handled such calculations.)
This was a major reason for moving to the Hindu-Arabic number system that we use today.
Still used in some places
However, Roman numerals are still used in certain situations, such as:
- The date a film was released: MLMLXXXII (1982)
- Special sporting events: Super Bowl XVII
- Generation title: King George II, Freddy Jones III
- Times in some clocks
- and other situations
Apparently, the reason to use the Roman numerals is to appear unique.
Summary
Roman numerals is a numbering system that uses certain letters of the alphabet and their combinations to indicate numbers. The system is based on seven major symbols, and counting is done by adding a symbol to the previous combination, except for certain numbers before an major symbol.
Problems with using Roman numerals caused the change to our present Hindu-Arabic symbols. However, Roman numerals are still used in special cases.
"When in Rome, do as the Romans do"
Resources and references
Websites
Roman Numerals - MathisFun.com
Roman numerals - Wikipedia
Convert Arabic to Roman Numerals - CalculateMe.com
Books
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Students and researchers
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www.school-for-champions.com/arithmetic/
roman_numerals.htm
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Roman Numerals