from maths.greatest_common_divisor import greatest_common_divisor """ Project Euler Problem 5: https://projecteuler.net/problem=5 Smallest multiple 2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder. What is the smallest positive number that is _evenly divisible_ by all of the numbers from 1 to 20? References: - https://en.wiktionary.org/wiki/evenly_divisible - https://en.wikipedia.org/wiki/Euclidean_algorithm - https://en.wikipedia.org/wiki/Least_common_multiple """ def lcm(x: int, y: int) -> int: """ Least Common Multiple. Using the property that lcm(a, b) * greatest_common_divisor(a, b) = a*b >>> lcm(3, 15) 15 >>> lcm(1, 27) 27 >>> lcm(13, 27) 351 >>> lcm(64, 48) 192 """ return (x * y) // greatest_common_divisor(x, y) def solution(n: int = 20) -> int: """ Returns the smallest positive number that is evenly divisible (divisible with no remainder) by all of the numbers from 1 to n. >>> solution(10) 2520 >>> solution(15) 360360 >>> solution(22) 232792560 """ g = 1 for i in range(1, n + 1): g = lcm(g, i) return g if __name__ == "__main__": print(f"{solution() = }")