Worked unit conversions from the lesson, each shown as the same amount on two rulers with different units. Distance: 3 nautical miles times 1.852 equals 5.556 kilometres. Speed: 15 knots times 1.852 equals 27.8 kilometres per hour, then divided by 3.6 equals 7.7 metres per second. Height: 400 feet times 0.3048 equals 122 metres. The bar for the starting value grows on the first ruler, drops to the second ruler, and the result appears. With mental estimates on, the rough rules are used instead: 1 nautical mile is roughly 2 kilometres, 2 knots is roughly 1 metre per second, and 3 feet is roughly 1 metre.
