Problem Project Euler Problem #001 asks us to find the sum of all natural numbers below 1000 that are multiples of 3 or 5 . This is a great beginner-friendly problem because it teaches one of the most important ideas in programming: Check every number, apply a condition, and accumulate the result. Idea A number should be added to the total if it is divisible by 3 or 5 . In Python, divisibility can be checked with the modulo operator: n % 3 == 0 Enter fullscreen mode Exit fullscreen mode This means: n leaves no remainder when divided by 3 . So the condition becomes: n % 3 == 0 or n % 5 == 0 Enter fullscreen mode Exit fullscreen mode Python solution total = 0 for n in range ( 1000 ): if n % 3 == 0 or n % 5 == 0 : total += n print ( total ) Enter fullscreen mode Exit fullscreen mode Explanation We start with: total = 0 Enter fullscreen mode Exit fullscreen mode Then we loop through every number below 1000 : for n in range ( 1000 ): Enter fullscreen mode Exit fullscreen mode For each number, we check whether it…