Get in touch
Questions, corrections, or a calculator you wish existed — this reaches me directly. If a number here looks wrong, please do say so: it is the most useful message you can send.
Worth writing about
Something looks wrong. A figure that does not match your bank or your bill. Tell me what you entered and what you expected, and I will check it.
A calculator that is missing. If you are working something out by hand or in a spreadsheet, it may be worth adding here.
Anything else. A question about how one of these works, or what a result means.
Replies usually take a day or two. Please do not send account numbers, passwords or anything else private — nothing here ever needs them.