Question: Is it his case number 30-100 or his Case Number 30-100?
Answer: First, thanks for asking the question. According to Gregg, a noun followed by a number or letter that indicates sequence is capitalized. I think since you are describing a specific case with the sequenced number, it is capitalized. If it just said “his case,” then it wouldn’t be capitalized, but it is like saying “his Mercedes Benz” rather than “his car.”
I hope that helps! And if any readers have questions, check out the Ask PTB page on the website proofthatblog.com.

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It’s time for “Confusing Words of the Week” where I take a set of two or three words that get confused and give you definitions and try to give you a memory trick to help you remember when to use which word. If you have words that confuse you, use Ask PTB or send an email to proofthatblog@gmail.com and they may appear here soon!
