Decimal to Octal

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```"""Convert a Decimal Number to an Octal Number."""

import math

# Modified from:
# https://github.com/TheAlgorithms/Javascript/blob/master/Conversions/DecimalToOctal.js

def decimal_to_octal(num: int) -> str:
"""Convert a Decimal Number to an Octal Number.

>>> all(decimal_to_octal(i) == oct(i) for i
...     in (0, 2, 8, 64, 65, 216, 255, 256, 512))
True
"""
octal = 0
counter = 0
while num > 0:
remainder = num % 8
octal = octal + (remainder * math.floor(math.pow(10, counter)))
counter += 1
num = math.floor(num / 8)  # basically /= 8 without remainder if any
# This formatting removes trailing '.0' from `octal`.
return f"0o{int(octal)}"

def main() -> None:
"""Print octal equivalents of decimal numbers."""
print("\n2 in octal is:")
print(decimal_to_octal(2))  # = 2
print("\n8 in octal is:")
print(decimal_to_octal(8))  # = 10
print("\n65 in octal is:")
print(decimal_to_octal(65))  # = 101
print("\n216 in octal is:")
print(decimal_to_octal(216))  # = 330
print("\n512 in octal is:")
print(decimal_to_octal(512))  # = 1000
print("\n")

if __name__ == "__main__":
main()
```