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Roman Numeral – Decimal Converter

Roman Numeral Converter

How To Use This Converter – Type a decimal number in the Decimal input field, or a Roman Numeral in the Roman field, and press Enter or Return on your keyboard or keypad. The other field will show the number you entered, converted to the other number system. The Roman input field accepts capital and/or lowercase letters, but outputs only capital letters. tip   TIP: Entry Errors – If the data you type into either field contains disallowed symbols for that field, the converter will automatically notify you. In that case, simply re-type valid data in the field of your choice and press Enter or Return. tip   TIP: You can Copy and Paste any of the fields by selecting the text in the field, then pressing Control-C to copy, and Control-V to paste.

Roman Numerals

The Roman Numeral System Roman Numerals are the number system of ancient Rome.   It is a decimal system, but not the modern positional notation Decimal system of everyday use.   For its symbols, the Roman Numeral system uses the following seven letters from the Latin alphabet: I, V, X, L, C, D, and M The ancient Romans wrote numerals with capital letters only, but in modern usage both capital and lowercase letters are allowed. The Roman Numeral symbols have these values: I=1, V=5, X=10, L=50, C=100, D=500, and M=1000 To represent large numbers the symbols are marked with an overline to indicate multiplication by 1000: I=1,000, V=5,000, X=10,000, L=50,000, C=100,000, D=500,000, M=1,000,000 The symbols are written in additive (or subtractive) order from left to right.   For example: I=1, II=2, III=3, IV=4 (5 minus 1) VI=6 (5 plus 1), VIII=8 (5 plus 3) IX=9 (10 minus 1) To let you enter large Roman Numerals into the converter, we use the underscore keyboard symbol instead of the overline (no keyboard symbol) to indicate multiplication by 1000.   For example, to represent decimal 158243, the converter writes: _C_L_VMMMCCXLIII Instead of the way it was written in ancient Rome: CLVMMMCCXLIII

Base-10

Decimal or Base-10 Number System Decimal is a radix-10 positional notation number system. Base-10 or radix-10 means that each Decimal "digit" represents a multiple of increasing powers of 10, from right to left, such as: ... 103, 102, 101, 100 The valid Decimal symbols are: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 For example, the Decimal number 927 represents the following numerical expression: (9 x 102) + (2 x 101) + (7 x 100) History of the Decimal Number System The modern Decimal number system, known as the Hindu-Arabic number system, originated in India around the 9th century CE. The system spread to the western world during the Middle Ages (1000 to 1300 CE) as a result of trade. Some scholars attribute the first documented use of a Decimal system to China in the 1st century BCE.

Roman Numeral Construction Rules

Additive Principle Roman Numerals are written in sequential additive order from left to right. Roman Numeral symbols have these values: I=1, V=5, X=10, L=50, C=100, D=500, and M=1000 So for example, the Roman Numeral MMVIII, is interpreted as the additive sequence: 1000 + 1000 + 5 + 3 = 2008 Subtractive Principle The Subtractive Principle dictates that when a symbol of smaller value comes before a symbol of larger value, the smaller value is subtracted from the larger value, and the result is added to the total. For example, in the Roman Numeral MCMXLIV, the symbol C (100) comes before M (1000), so subtract C from M (1000-100=900), and add the result (900) to the running total. Also, X (10) comes before L (50), so we subtract X from L (50-10=40), and add the result (40) to the running total. Finally, I (1) comes before V (5), so we subtract I from V (5-1=4), and add the result (4) to the total. So the Roman Numeral MCMXLIV, is interpreted as the additive and subtractive sequence: 1000+(1000-100)+(50-10)+(5-1) = 1944 Separate the Powers of 10 As a rule, build the highest power of 10 first, then add more Roman Numerals to the right for each successively smaller power of ten. For example, to build the Roman Numeral for decimal 3889, start with 3000 (MMM), add 800 (DCCC), add 80 (LXXX), and finally add 9 (IX): MMMDCCCLXXXIX

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