The formula with 16 substituted
miles = 16 ÷ 1.609344 = 9.942
The constant is an exact definition, not a rounded factor: the mile is 1.609344 km, the US gallon is 3.785411784 litres and the imperial gallon is 4.54609 litres. The Kilometres to Miles Converter explains where each comes from and gives a longer table.
At a walking pace of 5 km/h, 16 km takes about 192 minutes. At an easy running pace of 10 km/h it takes about 96. In metres it is 16,000.
What 16 kilometres means in practice
16 km is about 10 miles, the ten-mile road race distance popular in Britain and the US; the exact figure is 16.09 km. It is a classic stepping stone between a 10K and a half marathon.