The formula with 52 substituted
L/100km = 235.214583 ÷ 52 = 4.52
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 MPG to L/100km Converter explains where each comes from and gives a longer table.
The same 52 mpg (US) is 62.45 mpg on the imperial gallon, 4.52 L/100km and 22.11 km/L. If your 52 mpg figure came from a British source it already uses the imperial gallon, and the metric answer is 5.43 L/100km instead.
What 52 mpg (US) means in practice
52 mpg is 4.52 L/100km, the combined rating of the most efficient mid-size hybrid sedans on sale. Ten years ago that figure was exclusive to the Prius.