Simple script for naming the integers <10,000 (used in my math/proofs class)

number_names.py

from math import floor, log10
import sys

WORDS = {
  0: 'zero',
  1: 'one',
  2: 'two',
  3: 'three',
  4: 'four',
  5: 'five',
  6: 'six',
  7: 'seven',
  8: 'eight',
  9: 'nine',
  10: 'ten',
  11: 'eleven',
  12: 'tweleve',
  13: 'thirteen',
  14: 'fourteen',
  15: 'fifteen',
  16: 'sixteen',
  17: 'seventeen',
  18: 'eighteen',
  19: 'nineteen',
  # meaning & logic changes here
  20: 'twenty',
  30: 'thirty',
  40: 'fourty',
  50: 'fifty',
  60: 'sixty',
  70: 'seventy',
  80: 'eighty',
  90: 'ninety',
  # meaning & logic changes here
  100: 'hundred',
  1000: 'thousand'
}

def name_number(i: int):
    if not isinstance(i, int):
        raise TypeError("Can only name the integers")
    if i < 0:
        return f"negative {name_number(-i)}"
    try:
        return WORDS[i]
    except KeyError:
        pass
    assert i > 20
    if i < 100:
        ones_place = i % 10
        assert ones_place in range(0, 10)
        tens_place = i - ones_place
        assert tens_place % 10 == 0
        res = [WORDS[tens_place]]
        if ones_place != 0:
            res.append(WORDS[ones_place])
        return ' '.join(res)
    else:
        floor_log = floor(log10(i))
        # ie 100, 1000
        floor_power = 10**floor_log
        try:
            floor_power_name = WORDS[floor_power]
        except KeyError:
            raise ValueError(f"Number >=10**{floor_power} is too large to represent")
        multiple, leftover = divmod(i, floor_power)
        assert multiple in range(1, 10)
        assert leftover >= 0
        res = [WORDS[multiple], floor_power_name]
        if leftover != 0:
            leftover_name = name_number(leftover)
            if 'and' not in leftover_name:
                res.append('and')
            res.append(leftover_name)
        return ' '.join(res)

def main():
    try:
        number = int(sys.argv[1])
    except IndexError:
        print("Insufficent arguments! Please specify a single integer", file=sys.stderr)
        sys.exit(1)
    except ValueError:
        print(f"Must specify a valid integer: {sys.argv[1]!r}", file=sys.stderr)
        sys.exit(1)
    try:
        print(name_number(number))
    except ValueError as e:
        print(str(e), file=sys.stderr)
        sys.exit(1)

if __name__ == "__main__":
    main()