Python: Convert an integer to a roman numeral

Last update on July 09 2025 10:45:25 (UTC/GMT +8 hours)

1. Convert an Integer to a Roman Numeral

Write a Python class to convert an integer to a Roman numeral.

Sample Solution-1:

Python Code:

class py_solution:
    def int_to_Roman(self, num):
        val = [
            1000, 900, 500, 400,
            100, 90, 50, 40,
            10, 9, 5, 4,
            1
            ]
        syb = [
            "M", "CM", "D", "CD",
            "C", "XC", "L", "XL",
            "X", "IX", "V", "IV",
            "I"
            ]
        roman_num = ''
        i = 0
        while  num > 0:
            for _ in range(num // val[i]):
                roman_num += syb[i]
                num -= val[i]
            i += 1
        return roman_num


print(py_solution().int_to_Roman(1))
print(py_solution().int_to_Roman(4000))

Sample Output:

I                                                                                                             
MMMM  

Pictorial Presentation:

Flowchart:

Sample Solution-2:

Convert an integer to its roman numeral representation. Accepts value between 1 and 3999 (both inclusive).

• Create a lookup list containing tuples in the form of (roman value, integer).
• Use a for loop to iterate over the values in lookup.
• Use divmod() to update num with the remainder, adding the roman numeral representation to the result.

Python Code:

class py_solution:
    def int_to_Roman(self, num):
        lookup = [
            (1000, 'M'),
            (900, 'CM'),
            (500, 'D'),
            (400, 'CD'),
            (100, 'C'),
            (90, 'XC'),
            (50, 'L'),
            (40, 'XL'),
            (10, 'X'),
            (9, 'IX'),
            (5, 'V'),
            (4, 'IV'),
            (1, 'I'),
        ]
        res = ''
        for (n, roman) in lookup:
            (d, num) = divmod(num, n)
            res += roman * d
        return res
print(py_solution().int_to_Roman(1))
print(py_solution().int_to_Roman(500))
print(py_solution().int_to_Roman(755))
print(py_solution().int_to_Roman(1200))
print(py_solution().int_to_Roman(3456))

Sample Output:

I
D
DCCLV
MCC
MMMCDLVI

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python class that uses a dictionary mapping of numeral values and an iterative approach to convert a given integer to its Roman numeral representation.
• Write a Python class that implements a recursive algorithm to convert an integer to a Roman numeral, handling both small and large numbers.
• Write a Python class that validates input and raises exceptions for integers outside the accepted range for Roman numeral conversion.
• Write a Python class that takes a list of integers and returns a list of their Roman numeral representations using a class method.

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