Spreadsheet or document: where should the numbers live?

We make a document that holds numbers, so take this with the appropriate salt. It is still worth being clear about which jobs a spreadsheet does better, because using the wrong one is slower than either.

A spreadsheet is the right place when

• The numbers are the work: modelling, budgets with dozens of interacting assumptions, anything where you want to see and edit every cell.
• You need arbitrary formulas, lookups across sheets, or somebody downstream expects a spreadsheet.
• The output is the sheet itself, not a conclusion about it.

A document is the right place when

• The point is what the numbers mean, and somebody has to read it: a weekly update, a client report, a proposal, a recommendation.
• You want the figures inside your sentences to stay right when the data changes, which a spreadsheet cannot do for prose.
• You want to send the conclusion without sending the rows. A document can hide the data behind it; a shared sheet is all or nothing.
• The people reading do not want to learn formulas, and the people writing would rather ask in plain words.

The usual answer is both

Keep the ledger in a sheet, because that is what a sheet is for, and link it to the document you actually send. The sheet stays the source; the document is the part with a point in it.