TheAlgorithms/Python · error · ValueError

This function only accepts non-negative integers

Error message

This function only accepts non-negative integers

What it means

convert_small_number raises this ValueError when num is negative. The helper only formats numbers 0-99 using ONES/TEENS/TENS word tables, which have no negative entries; the top-level convert_number handles the sign itself by prepending 'negative', so the small-number helper never needs to.

Source

Thrown at conversions/convert_number_to_words.py:122

    >>> convert_small_number(10)
    'ten'
    >>> convert_small_number(15)
    'fifteen'
    >>> convert_small_number(20)
    'twenty'
    >>> convert_small_number(25)
    'twenty-five'
    >>> convert_small_number(-1)
    Traceback (most recent call last):
    ...
    ValueError: This function only accepts non-negative integers
    >>> convert_small_number(123)
    Traceback (most recent call last):
    ...
    ValueError: This function only converts numbers less than 100
    """
    if num < 0:
        raise ValueError("This function only accepts non-negative integers")
    if num >= 100:
        raise ValueError("This function only converts numbers less than 100")
    tens, ones = divmod(num, 10)
    if tens == 0:
        return NumberWords.ONES.value[ones] or "zero"
    if tens == 1:
        return NumberWords.TEENS.value[ones]
    return (
        NumberWords.TENS.value[tens]
        + ("-" if NumberWords.ONES.value[ones] else "")
        + NumberWords.ONES.value[ones]
    )


def convert_number(
    num: int, system: Literal["short", "long", "indian"] = "short"
) -> str:
    """

View on GitHub (pinned to f5988cc097)

Solutions

1. Call convert_number(num) instead — it handles negatives and large numbers end-to-end
2. If you must use the helper, strip the sign first and add the word yourself
3. Clamp inputs to 0-99 before calling: max(0, min(99, num))

Example fix

# before
convert_small_number(-5)
# ValueError: This function only accepts non-negative integers

# after
convert_number(-5)  # 'negative five'

if num < 0:
    raise ValueError('use convert_number for negatives')
convert_small_number(num)

def is_small_non_negative(n) -> bool:
    return isinstance(n, int) and 0 <= n < 100

try:
    convert_small_number(n)
except ValueError:
    return convert_number(n)  # full converter handles any int

When it happens

Trigger: convert_small_number(-1); calling convert_small_number directly on parsed negative input instead of going through convert_number.

Common situations: Bypassing convert_number and reusing the internal helper; debt/temperature values passed to a helper designed for digit-group formatting.

Related errors

• This function only converts numbers less than 100
• Invalid numbering system
• Input number is too large
• Invalid 'from_type' value: {from_type!r}.\nConversion abbrev
• Invalid 'to_type' value: {to_type!r}.\nConversion abbreviati

AI-assisted analysis of TheAlgorithms/Python@f5988cc097 (2026-08-14). Data as JSON: /api/errors/7e61d6e558b564c9. Report an issue: GitHub.