A square hectometer (often abbreviated as hm²) is a unit of area in the International System of Units (SI). It represents a square with sides that each measure 100 meters (10,000 centimeters) in length.
One square hectometer is equal to 10,000 square meters (m²) because each side of the square is 100 meters long, and when you square that length, you get 10,000 square meters.
To put it in perspective, a square hectometer is equivalent to 0.01 square kilometers (km²) because 1 square kilometer is equal to 100 hectares.
Square hectometers are not as commonly used as some other units of area, but they can be helpful for measuring large land areas, especially in some scientific and land management contexts.
The "acre (US survey)" is a unit of area used specifically in the United States for land surveying and legal property descriptions. It is different from the standard acre used in other parts of the world. The U.S. survey acre is based on the U.S. survey foot, which is a historical unit of length used in land surveying in the United States. The U.S. survey foot is slightly different from the international foot.
One acre (US survey) is equal to approximately 4,046.872609874252 square meters (m²) or about 0.40468726 hectares (ha).
This unit is used in various land-related applications, especially in the United States, where the U.S. survey acre is employed for legal and historical reasons in land surveys, property descriptions, and land records. It's important to be aware of the specific units being used when dealing with land measurements in the United States to avoid discrepancies or errors.