Nymphenburg Palace in Munich was the featured picture at Wikipedia recently, but what caught my eye was the area values given for the palace park in the caption: “200-hectare (494-acre) park.” That looks like a case where a unit conversion introduces false precision. A round number like 200 suggests low precision, so 200 hectares might mean anything from 150 to 250 hectares, but 494 suggests higher precision, between 493.5 and 494.5 acres in this case.
It looks like someone took a round number (200) and multiplied it by the hectare-to-acre conversion factor (1.47) to get a precise number (494). It would be better to go back to the original precise number of hectares, convert that to acres, and then round to the desired level of detail.
Trying to find the actual size of the park was more difficult than I expected. After finding a few places that listed the size as 200 acres, it was evident a different kind of error was also occurring, but it wasn’t clear whether hectares or acres was correct. Google hit count comparisons didn’t help. Searching for Nymphenburg Palace park “200 acre” gave 125 hits while Nymphenburg Palace park “200 hectare” gave 101 hits.
Just to be sure, I found the park on Google Maps and measured it myself with an online planimeter tool. The area of my rough polygon was 225 hectares, so that settles the 200 acre versus 200 hectare issue for me.
Eventually, I found the German language Wikipedia page for the Nymphenburg park, and it provided two areas, 180 and 229 hectares, with apparent authority. Translation:
The park inside the garden wall has a size of 180 hectares, the area of the entire facility is 229 hectares.
200 hectares could represent either 180 or 229. Exactly 180 hectares is 445 acres and 229 hectares is 565 acres, so you need to know where the 200 came from in order to know how to represent it in acres. It could be correct to say 400, 500, or 600 acres.