What is the 7 trick in multiplication?

Excuse me, could you elaborate on what you mean by "the 7 trick in multiplication"? Is it a specific method or shortcut for multiplying numbers involving the digit 7? If so, could you provide more context or details about this trick? It's not a commonly known term in the field of mathematics or finance, so I'm curious to learn more about it. Alternatively, if you're referring to a broader concept or strategy related to multiplication, I'd be happy to discuss that as well.