Hi Brendan and PDS
Back again after watching some TV and doing the washing up. Many thanks for your hints and corrections. I've now finished and am just trying to spot the theme answers. So far I've only got seven!
Like PDS, I did a lot of maths at Uni, but it was a very long time ago and few of the common ones are here. But my Chambers dictionary has a list.
My husband knew 18ac, but he is much more of a computer nerd than I am.
I was so pleased last week when I finished it all on my own, but the forum was down and I couldn't boast. But I found this one hard. I hope to be back next week.