A square decameter (often abbreviated as dam²) is a unit of area in the International System of Units (SI). It represents a square with sides that each measure 10 meters (1,000 centimeters) in length.
One square decameter is equal to 100 square meters (m²) because each side of the square is 10 meters long, and when you square that length, you get 100 square meters.
Square decameters are not as commonly used as some other units of area, but they can be used to describe moderate-sized land areas, and they are a part of the metric system for measuring area.
A square kilometer (often abbreviated as km²) is a unit of area in the International System of Units (SI). It represents a square with sides that each measure 1 kilometer in length.
One square kilometer is equal to 1,000,000 square meters (m²) because there are 1,000 meters in a kilometer, and when you square that length, you get 1,000 * 1,000 = 1,000,000 square meters.
To visualize the size of a square kilometer, you can imagine a square plot of land, each side of which measures 1 kilometer (approximately 0.621 miles). It's a commonly used unit to measure land area, particularly in countries that use the metric system.