The formula with 2.3 substituted
miles = 2.3 ÷ 1.609344 = 1.429
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, 2.3 km takes about 28 minutes. At an easy running pace of 10 km/h it takes about 14. In metres it is 2,300.
What 2.3 kilometres means in practice
At 2.3 km you are at 1.43 miles, just short of the mile and a half that several police and military fitness tests use. If that test is what brought you here, the exact figure is 2.414 km.