Is my math correct?

[Just_Build_It]

I have previously searched for a scale calculator but wasn't sure how to word it. I reworded my question in the search and found that scale Calculator and showed my math was correct. Its the same formula Ives been using in the past and I just needed a way to double check myself.

Thanks for your time gentlemen I always appreciate the help. (Fill in the blank.)_________ knows that I could use it.