Question

Write the corresponding Hindu-Arabic numerals for the following.
CCCXXIX
Express the given Roman number XLIX in English numeral.

Answer 1

Hint:- Let's break the roman numbers into small parts and then change them to English numerals to find the numeral of CCCXXIX. So, let us make the roman number table for different English numerals.

Complete step-by-step solution -
As we know that CCCXXIX is written in Roman numbers, so let us make a roman number table for different numbers.

English Numeral	Roman Numbers
1	I
5	V
10	X
50	L
100	C
500	D
1000	M

Now each roman number can occur only maximum of three times consecutively. Like III is possible and is equal to 3 but IIII is not possible and is not equal to 4.
And if there are two different roman numbers placed consecutively then if a smaller roman number is on the right of the larger number then the equivalent number will be larger plus smaller (example VI is equal to 6).
And if the smaller is on the left of the larger then the equivalent number will be larger minus smaller (example IV is equal to 4).
So, now let us find the English numeral of CCCXXIX.
As we can see from the above table that C is equal to 100.
And there are three C in the starting of CCCXXIX. So, CCC will be equal to 100 + 100 + 100 = 300.
Now there are two X continuously after C. So, XX = 10 + 10 = 20
After that we had to find the value of IX.
And I am on the left of the X. So, IX will be 10 – 1 = 9.
Now IX is on the write of XX and XX is on the right of CCC. So, CCCXXIX = 300 + 20 + 9 = 329.
Hence, the Hindu-Arabic numeral of CCCXXIX is 329.

Note:- If any roman number is such that there are four consecutive same numbers present in it then the number will not be valid like XXXX is not equal to 40 rather 40 is written as XL. So, first we had to find the largest roman numeral letter in the given number like in LDXI first we find that D is equal to 500 and then we had to find the second largest roman letter that is L which is equal to 50 and then L is on the left of D. So, LD will be equal to 500 – 50 = 450. And then we find that X is equal to 10 and I is equal to 1 which is on the right of X. So, XI is equal to 11 and XI is on the right of LD. So, overall number LDXI will be equal to 450 + 11 = 461. This is the efficient way to find the Hindu-Arabic numeral of given roman number.