In 1995, British authorities warned that certain contraceptive pills doubled the risk of thrombosis. Doubling here meant going from about 1 case in 7,000 to 2 in 7,000. But only the “100%” stuck in people's minds: many women stopped taking the pill, and the scare is estimated to have led to around 13,000 additional abortions in England and Wales the following year.
How many different structures can you build with six classic 2-by-4 Lego bricks of the same colour? The company used to quote just over 102 million. In 2005, Danish mathematician Søren Eilers recounted everything by computer: 915,103,765 combinations. The official estimate had been too low by a factor of about nine.
Fold an A4 sheet in half and you get an A5 with the same proportions. That only works for one ratio between length and width: about 1.414, the square root of 2. The A0 format measures exactly one square metre, and A4 is a sixteenth of it. With standard 80-gram-per-square-metre paper, an A4 sheet therefore weighs exactly 5 grams.