Anyone who is trying vaguely to control their weight and still eats tasty, nasty processed foods — me, for instance — gets used to playing the game of 'guess how many calories there are in the packet'. Today I bought the bag of sweets pictured above, and discovered a new difficulty level.

The rules of the guessing game go like this: Manufacturers print two calorie counts on the front of a typical packet - one for 100g, in small type, and one for 'one typical serving', in bigger type. The typical serving size, as far as I can tell, is determined by how large a fraction of the packet you can consume before passing some psychologically significant number of calories. With frozen pizzas, for example, the upper limit is somewhere around 600: so a goat's-cheese and roasted vegetable pizza will consist of two 450-calorie servings (that'll be a 900-calorie supper, then), while the same product range's cheesy meat feast with extra meat and extra cheese will be three servings of 590 each (1,770; I probably shouldn't).

With sweets, the psychological limit tends to be 100 calories, even if that's one-third of a chocolate bar bound together by hard yet tacky nougat. And then, it turns out, there are Rowntrees Randoms. The big calorie count is — no great surprise — 92. And the serving size? 'Six sweets'. How big are the sweets? How many are there in the bag? You'll have to tear it open to find out.

Or you could ask me. As a public service, I counted as I ate. There are 12 sweets per packet of Randoms. Six sweets is half a packet. Why not just say that? Here is my guess: because then anyone who can multiply by two in their head would know that this is a 184-calorie indulgence, not a 92-calorie one. And that wouldn't be playing the game.