Sum of all multiples is not supposed to include number passed to function.
Reason why other tests pass is because they do not fulfill operation condition themselves.
I’ve edited your post for readability. When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make easier to read.
See this post to find the backtick on your keyboard. The “preformatted text” tool in the editor (</>) will also add backticks around text.