In the new year I'm going to be doing some of those sorts of videos for people targeting particular grades so there will be one for people aiming for an 8 or a 9 that will have plenty of hard questions. Probably won't be able to get it out till February though.
Sorry only just saw this comment. You're quite right. There is a mistake earlier on as Sofia says where I calculate 25+40 divided by two and then multiply by 5. I say it's 112.5 whereas in fact it should be 162.5. When you add up all the values with this correct one it gives you 712.5. So I think I must have calculated it correctly on paper beforehand and got that overall correct answer but said it wrong in the video.
