Privacy

Nothing you type here is sent anywhere. The problems are generated in your browser, the answers are checked in your browser, and there is no endpoint on this site that would accept them.

There is nothing to sign up for. We never ask for a pupil's name, a class list or an email address, and the name line on the printed sheet is ink on paper — it exists only after you print.

An assignment link carries the set after the #, for example #seed=k7f2x1. Browsers never send that part of an address to a server, so the set you share reaches the people you send it to and nobody else.

Visits are counted without cookies and without identifiers: the day, whether this browser has been here before, the page, the referring site's host, whether the device has a touch screen, and the browser's language. That is enough to tell whether anybody is using the site and nothing like enough to tell who. There is no third-party analytics script on sumcomb.com and there will not be one.

Your browser stores one thing of its own: which theme you chose, and the day it first visited, so that a returning visit can be counted once. Clearing site data removes both.

The screen version of a practice page carries advertising below the sheet. The printed sheet carries none — that is the whole reason the problems are worked on the page rather than downloaded as a file.