“Hmm, ’bout twenty I reckon.” said the man. It was a better guess than most. Last week a young lad had come in and estimated that there were sixty-six billion sweets in the jar. It was such a ridiculous guess that I had to make him aware of his own incompetence. I informed him that the volume of the sweets was on average one and a half cubic centimetres. The jar was no bigger than his head. I told him that sixty-six billion sweets would take up roughly a hundred thousand cubic metres, which would be so many that they wouldn’t all fit in this room without spilling out onto the street. Anyone in the room would drown in gelatin. His family and everyone he loved would perish in a colourful sludge. Even if they tried to eat their way out, either their stomachs would explode or their brains would be fried by sugar overdose. And if we tried to compact the sweets so that they’d fit in the jar, the resulting pressure would result in a heat so high that the whole street would burst into flames, and everyone would be roasted. Or it might even form a neutron star, sucking in all matter in the vicinity and torching the Earth. And it would all be his fault. Yes, I did call him a terrorist. Yes, he did cry. But it served him right for being a bad guesser.