Python How to Convert Number to Words Easily

Use the num2words library in Python by installing it with pip install num2words and then call num2words(number) to convert a number to words.

Examples

Input5

Outputfive

Input123

Outputone hundred and twenty-three

Input0

Outputzero

How to Think About It

To convert a number to words, think about how humans say numbers aloud by breaking them into parts like hundreds, tens, and ones, then mapping each part to its word form. Using a library like num2words automates this process by handling all these rules internally.

Algorithm

1

Get the input number.

2

Use a function or library that maps the number to its word form.

3

Return or print the word representation.

Code

python

from num2words import num2words

number = 123
words = num2words(number)
print(words)

Output

one hundred and twenty-three

Dry Run

Let's trace converting 123 to words using num2words.

1

Input number

number = 123

2

Convert to words

words = num2words(123) # returns 'one hundred and twenty-three'

3

Print result

print(words) # outputs 'one hundred and twenty-three'

Step	Value
Input	123
Converted	one hundred and twenty-three
Output	one hundred and twenty-three

Why This Works

Step 1: Import library

The num2words library provides a ready function to convert numbers to words.

Step 2: Call conversion

Calling num2words(number) returns the English words for the number.

Step 3: Print output

Printing the result shows the number spelled out as words.

Alternative Approaches

Manual mapping with dictionaries

python

def number_to_words(n):
    ones = ['zero','one','two','three','four','five','six','seven','eight','nine']
    if 0 <= n < 10:
        return ones[n]
    return 'Number out of range'

print(number_to_words(5))

Simple but only works for single digits; not scalable for large numbers.

Using inflect library

python

import inflect
p = inflect.engine()
print(p.number_to_words(123))

Another popular library that converts numbers to words with more options.

Complexity: O(1) time, O(1) space

Time Complexity

Conversion is done by direct lookup and simple rules inside the library, so it runs in constant time.

Space Complexity

Uses fixed internal data for words, so space is constant regardless of input size.

Which Approach is Fastest?

Using num2words or inflect is fast and reliable; manual methods are slower and limited.

Approach	Time	Space	Best For
num2words library	O(1)	O(1)	All number sizes, easy use
inflect library	O(1)	O(1)	Flexible word formatting
Manual mapping	O(1)	O(1)	Very small numbers, learning purpose