'Can I help you?'
'Yes, I'm looking for a 30-centimetre round cake tin.'
'Hm. Let's have a look. We have this 22-centimetre cake tin.'
'Yes. But I need a 30-centimetre cake tin.'
'A round tin?'
'Preferably. It doesn't really matter.'
'Hm. A 30-centimetre round tin.'
'Yes.'
'I don't think we have one.'
'That's OK.'
'Sorry.'
'That's OK.'
'There must be something—'
'No really, that's OK.'
'I mean, 30 centimetres is very specific, isn't it?'
'Good heavens, so it is! I had thought that it might be an idea to work out how big a cake to make in order that everyone at my party receive a portion of delicious sponge—but now that I think of it, you're right. I'm being precious. I'll just take this novelty nine-centimetre baking tin in the shape of a goldfish instead. In fact, you know what? I don't even need a cake. I'll just give the guests a bag of flour and a spoon. Thanks!'
See if you can spot where it stopped being true.
