Can I have a little spreadsheet within my Pages document, do a little bit of calculations?
I found the "Table" feature. But that seems to support only static content, not formulas for calculating values.
You can create a formula in a Pages table simply by starting to write in any cell with an equal ("=") sign as described in the "Calculate values using data in table cells in Pages on Mac" Apple Pages support webpage. The outcome of the formula will be updated automatically when the formula or the content of any cell included in the formula is modified. If you need to have a Pages table cell to literally show an equal sign at its beginning rather than contain a working formula, simply type in a single quote (‘) before the equal sign.
While it is not possible to embed a Numbers table into a Pages document like an Excel sheet can be into a Word document, you can paste a Numbers table to Pages; the formulas in the Numbers table will be preserved in the Pages table unless they refer to a cell in a table that has not been pasted simultaneously from Numbers. Note, however, the Pages table will not be linked to the original Numbers document in any case and therefore will not be updated as the Numbers table it is copied from is changed.