How to read and write roman numerals?
Hundreds of year ago, the Romans had a system of numbers which had only
seven symbols. Each symbol had a different value and there was no symbol
for 0.
The symbol of Roman Numerals and their values are:
Romans used different combinations of symbols to write numbers using adding and subtraction.
For reading and writing numbers upto 50 we need only the first 4 symbols.
I V X L
Rules for the first five symbols
Multiplication Rule:
When a symbol is repeated in succession, we multiply the value of the numeral by the number of times it is repeated.
A symbol cannot be repeated more than three times in succession.
For example:
II = 1 × 2 = 2
XX = 10 × 2 = 20
XXX = 10 × 3 = 30
We cannot write 40 as XXXX.
The symbol cannot be repeated more than three times.
Addition Rule:
Writing a smaller number to the right of a larger number means the numbers have to be added.
For example:
VI = 5 + 1 = 6
XI = 10 + 1 = 11
XII = 10 + 1 + 1 = 12
Subtraction Rule:
Writing a smaller number to the left of a larger number means that the
smaller number has to be subtracted from the larger number. The symbol 1
can be used for subtraction from V and X only. The symbol X can be
subtracted only from L and C.
For example:
IV = 5  1 = 4
IX = 10  1 = 9
XL = 50  10 = 40
The symbol V cannot be repeated or subtracted.
We do not repeat V twice to get 10. We already have a symbol for 10. So VV for writing 10 is not correct.
We do not subtract 5 from any symbol. VX is not correct.
A list of Roman Numerals and their value are given below:
Writing Numbers in Roman Numerals:
For example:
1. Write the Roman Numerals for 27. Break up the number into Tens and Ones.
27 = 20 + 7
Write the symbol for 20 (XX) and place the symbol for 7 (VII) after it.
27 convert roman numerals as XXVII
2. Write the Roman numeral number for 43.
43 = 40 + 3
Symbol for 40 XL
Symbol for 3 III
Roman Numerals for 43 is XLIII.
Reading Roman Numerals:
Look out for a subtraction operation. Do the subtraction before adding the numbers.
For example:
1. XXIV I = 1 V = 5 IV = 4
XX = 20
IV = 4
Hindu –Arabic numeral for XXIV is 24.
2. XIX IX = 9
Hindu –Arabic number for XIX = 19
3. XXXII
In this example no subtraction is needed.
XXX = 30
II = 2
Hindu –Arabic number for XXXII = 32
Related Concept
● Rules for Formation of Romannumerals
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