Two of the most immediately useful things you can do with Claude have nothing to do with writing: reading documents you don't have time to read, and making sense of spreadsheets you didn't build.
Documents: read once, ask many times
Upload a contract, report, or research paper and instead of one summary request, treat it like an interview. Ask a series of specific questions: "What are the payment terms?" "Are there any auto-renewal clauses?" "Summarize the risks section in plain English." Claude keeps the document in context for the whole conversation, so each follow-up gets sharper instead of starting over.
For long documents, ask for a structured pass first: "Give me the document's structure as a table of contents with one line per section," then drill into the sections that matter. It's faster than reading linearly and you won't miss the parts you'd normally skim past.
Spreadsheets: describe the mess, not just the data
Upload a spreadsheet and describe what's wrong with it in plain language: "This has duplicate rows, inconsistent date formats, and I need totals by region." Claude can help you clean it, write the formulas you need, or explain formulas someone else already wrote that you don't understand.
A genuinely underused move: paste a formula that's throwing an error and just ask "why is this broken and how do I fix it?" It's often faster than searching a forum for your exact error message.
The habit that saves the most time
Instead of exporting data into a chat as a copy-pasted table, attach the actual file. Claude reads structure and context from the real file far better than from a wall of pasted numbers, and you avoid the formatting errors that creep in with copy-paste.
A word of caution
For anything going into a financial report or legal document, treat Claude's output as a very strong first draft, not a final answer. Spot-check numbers, and where precision genuinely matters, verify the calculation independently. That's not a Claude-specific rule - it's just good practice with any AI-assisted work.